diff --git a/Lab_10/studentCourseEvaluation.cpp b/Lab_10/studentCourseEvaluation.cpp
index 95843c5..ce74fcb 100644
--- a/Lab_10/studentCourseEvaluation.cpp
+++ b/Lab_10/studentCourseEvaluation.cpp
@@ -4,181 +4,186 @@
 using namespace std;
 
 // creating a class named "Student"
-class Student
+void TakeData()
 {
-private:
-	string student_id;
-	string student_name;
-	double OOP2_Score;
-	double math_Score;
-	double english_Score;
-	double total_Score;
-	double ctotal()
-	{
-		total_Score = OOP2_Score + math_Score + english_Score;
-		return total_Score;
-	}
-
-public:
-	void TakeData()
-	{
-		cout << "ID : ";
-		cin >> student_id;
-		cout << "Name: ";
-		cin >> student_name;
-		cout << "OOP2: ";
-		cin >> OOP2_Score;
-		cout << "Math: ";
-		cin >> math_Score;
-		cout << "English: ";
-		cin >> english_Score;
-		ctotal();
-	}
-	void showData()
-	{
-
-		cout << "ID: " << student_id << endl;
-		cout << "Name: " << student_name << endl;
-		cout << "OOP2: " << OOP2_Score << endl;
-		cout << "Math: " << math_Score << endl;
-		cout << "English: " << english_Score << endl;
-		cout << "Total score: " << total_Score << endl;
-	}
-};
+    // PRECOGS_FIX: perform robust input validation and allow spaces in name using getline
+    #include <limits>
+
+    cout << "ID : ";
+    if (!(cin >> student_id)) {
+        cin.clear();
+        string tmp;
+        getline(cin, tmp);
+        cout << "Invalid ID input. Aborting input." << endl;
+        return;
+    }
+
+    // consume the trailing newline before using getline for full name
+    cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+    cout << "Name: ";
+    if (!std::getline(cin, student_name) || student_name.empty()) {
+        cout << "Invalid name input. Aborting input." << endl;
+        return;
+    }
+
+    auto readValidatedDouble = [&](const string &prompt, double &out, double minVal = 0.0, double maxVal = 1000.0) {
+        while (true) {
+            cout << prompt;
+            if (cin >> out) {
+                if (out >= minVal && out <= maxVal) {
+                    break;
+                }
+                cout << "Value out of accepted range (" << minVal << " - " << maxVal << "). Try again." << endl;
+            } else {
+                // PRECOGS_FIX: clear stream and discard invalid token before retry
+                cin.clear();
+                string discard;
+                getline(cin, discard);
+                cout << "Invalid numeric input. Try again." << endl;
+            }
+        }
+    };
+
+    readValidatedDouble("OOP2: ", OOP2_Score, 0.0, 100.0);
+    readValidatedDouble("Math: ", math_Score, 0.0, 100.0);
+    readValidatedDouble("English: ", english_Score, 0.0, 100.0);
+
+    ctotal();
+}
 
 // creating a class named "Employee"
-class Employee
+double total_salary()
 {
-private:
-	string Employee_ID;
-	string Employee_Name;
-	int Hours;
-	int Rate;
-
-public:
-	void setEmployee_ID(string x)
-	{
-		Employee_ID = x;
-	}
-	string getEmployee_ID()
-	{
-		return Employee_ID;
-	}
-	void setEmployee_Name(string y)
-	{
-		Employee_Name = y;
-	}
-	string getEmployee_Name()
-	{
-		return Employee_Name;
-	}
-	void setHours(int z)
-	{
-		Hours = z;
-	}
-	int getHours()
-	{
-		return Hours;
-	}
-	void setRate(int i)
-	{
-		Rate = i;
-	}
-	int getRate()
-	{
-		return Rate;
-	}
-	double total_salary()
-	{
-		int total;
-		total = Hours * Rate;
-		return total;
-	}
-};
+    // PRECOGS_FIX: validate inputs and perform multiplication in 64-bit to avoid 32-bit overflow
+    #include <limits>
+
+    long long h = static_cast<long long>(Hours);
+    long long r = static_cast<long long>(Rate);
+
+    // Basic validation: no negative hours/rate allowed for salary computation
+    if (h < 0 || r < 0) {
+        return 0.0;
+    }
+
+    const long long maxAllowed = std::numeric_limits<long long>::max();
+    if (r != 0 && h > maxAllowed / r) {
+        // Overflow would occur. Cap at max representable or handle as error.
+        return static_cast<double>(maxAllowed);
+    }
+
+    long long total = h * r;
+    return static_cast<double>(total);
+}
 
 int main()
 {
-	int choice;
-	cout << "1. Student" << endl;
-	cout << "2. Employee" << endl;
-	cout << "Your choice: ";
-	cin >> choice;
-	cout << endl;
-
-	Student student;   // creating an object of a class "Student"
-	Employee employee; // creating an object of a class "Employee"
-	switch (choice)
-	{
-	case 1:
-	{
-		student.TakeData();
-		cout << endl;
-		student.showData();
-	}
-	break;
-	case 2:
-	{
-		while (true)
-		{
-			system("cls");
-			int choice_employee;
-
-			cout << "1. Input Employee Details\n";
-			cout << "2. Display Employee Details\n";
-			cout << "3. Display Salary\n";
-			cin >> choice_employee;
-			switch (choice_employee)
-			{
-			case 1:
-			{
-				string x, y;
-				int z, i;
-				system("cls");
-				cout << "\t\t\tEmployee information\n";
-				cout << "Employee_ID: ";
-				cin >> x;
-				cout << "Employee_Name: ";
-				cin >> y;
-				cout << "Number of worked Hours: ";
-				cin >> z;
-				cout << "Rate per Hour: ";
-				cin >> i;
-				cout << endl;
-				employee.setEmployee_ID(x);
-				employee.setEmployee_Name(y);
-				employee.setHours(z);
-				employee.setRate(i);
-				system("pause");
-			}
-			break;
-			case 2:
-			{
-				system("cls");
-				cout << "ID: " << employee.getEmployee_ID() << endl;
-				cout << "Name: " << employee.getEmployee_Name() << endl;
-				cout << "Hours: " << employee.getHours() << endl;
-				cout << "Rate: " << employee.getRate() << endl;
-				system("pause");
-			}
-			break;
-			case 3:
-			{
-				system("cls");
-				cout << "Total salary: " << employee.total_salary() << endl;
-				system("pause");
-			}
-			break;
-			default:
-				cout << "Incorrect input! Try again!" << endl;
-				break;
-			}
-		}
-	}
-	break;
-	default:
-		cout << "Incorrect input! Try again!" << endl;
-		break;
-	}
-	system("pause");
-	return 0;
+    // PRECOGS_FIX: remove unsafe system() use and replace with portable/controlled clear and pause behavior
+    #include <limits>
+
+    auto clearScreen = []() {
+        // Best-effort portable clear: print several newlines instead of calling system("cls")/system("clear")
+        for (int i = 0; i < 50; ++i) std::cout << '\n';
+    };
+
+    auto pausePrompt = []() {
+        std::cout << "Press Enter to continue..." << std::endl;
+        std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+        std::cin.get();
+    };
+
+    int choice;
+    std::cout << "1. Student" << std::endl;
+    std::cout << "2. Employee" << std::endl;
+    std::cout << "Your choice: ";
+    if (!(std::cin >> choice)) {
+        std::cerr << "Invalid input. Exiting." << std::endl;
+        return 1;
+    }
+    std::cout << std::endl;
+
+    Student student;   // creating an object of a class "Student"
+    Employee employee; // creating an object of a class "Employee"
+    switch (choice)
+    {
+    case 1:
+    {
+        student.TakeData();
+        std::cout << std::endl;
+        student.showData();
+    }
+    break;
+    case 2:
+    {
+        while (true)
+        {
+            clearScreen(); // PRECOGS_FIX: avoid system("cls") to reduce execution of shell commands
+            int choice_employee;
+
+            std::cout << "1. Input Employee Details\n";
+            std::cout << "2. Display Employee Details\n";
+            std::cout << "3. Display Salary\n";
+            if (!(std::cin >> choice_employee)) {
+                std::cin.clear();
+                std::string discard;
+                std::getline(std::cin, discard);
+                std::cout << "Invalid selection. Try again." << std::endl;
+                pausePrompt(); // PRECOGS_FIX: replace system("pause") with controlled prompt
+                continue;
+            }
+            switch (choice_employee)
+            {
+            case 1:
+            {
+                std::string x, y;
+                int z, i;
+                clearScreen();
+                std::cout << "\t\t\tEmployee information\n";
+                std::cout << "Employee_ID: ";
+                if (!(std::cin >> x)) { std::cin.clear(); std::getline(std::cin, x); }
+                std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
+                std::cout << "Employee_Name: ";
+                std::getline(std::cin, y);
+                std::cout << "Number of worked Hours: ";
+                while (!(std::cin >> z)) { std::cin.clear(); std::string discard; std::getline(std::cin, discard); std::cout << "Invalid hours. Enter integer: "; }
+                std::cout << "Rate per Hour: ";
+                while (!(std::cin >> i)) { std::cin.clear(); std::string discard; std::getline(std::cin, discard); std::cout << "Invalid rate. Enter integer: "; }
+                std::cout << std::endl;
+                employee.setEmployee_ID(x);
+                employee.setEmployee_Name(y);
+                employee.setHours(z);
+                employee.setRate(i);
+                pausePrompt();
+            }
+            break;
+            case 2:
+            {
+                clearScreen();
+                std::cout << "ID: " << employee.getEmployee_ID() << std::endl;
+                std::cout << "Name: " << employee.getEmployee_Name() << std::endl;
+                std::cout << "Hours: " << employee.getHours() << std::endl;
+                std::cout << "Rate: " << employee.getRate() << std::endl;
+                pausePrompt();
+            }
+            break;
+            case 3:
+            {
+                clearScreen();
+                std::cout << "Total salary: " << employee.total_salary() << std::endl;
+                pausePrompt();
+            }
+            break;
+            default:
+                std::cout << "Incorrect input! Try again!" << std::endl;
+                pausePrompt();
+                break;
+            }
+        }
+    }
+    break;
+    default:
+        std::cout << "Incorrect input! Try again!" << std::endl;
+        break;
+    }
+    pausePrompt();
+    return 0;
 }
diff --git a/Lab_16/Source.cpp b/Lab_16/Source.cpp
index 8f98917..d74eddd 100644
--- a/Lab_16/Source.cpp
+++ b/Lab_16/Source.cpp
@@ -57,35 +57,34 @@ class Staff
 	}
 };
 
-class Teacher : public Staff
+void getdata()
 {
-protected:
-	string subject;
-	int publications;
-
-public:
-	Teacher()
-	{
-		subject = "Unknown";
-		publications = 0;
-	}
-	void getdata()
-	{
-		Staff::getdata_code();
-		Staff::getdata_name();
-		cout << " Enter subject: ";
-		cin >> subject;
-		cout << " Enter number of publications: ";
-		cin >> publications;
-	}
-	void showdata()
-	{
-		Staff::showdata_code();
-		Staff::showdata_name();
-		cout << " Subject: " << subject << endl
-			 << " Publications: " << publications << endl;
-	}
-};
+    Staff::getdata_code();
+    Staff::getdata_name();
+
+    std::cout << " Enter subject: ";
+    std::string tmp_subj;
+    std::getline(std::cin >> std::ws, tmp_subj);
+    const size_t MAX_SUBJECT_LEN = 100;
+    if (tmp_subj.size() > MAX_SUBJECT_LEN) tmp_subj = tmp_subj.substr(0, MAX_SUBJECT_LEN);
+    subject = tmp_subj;
+
+    // Validate integer input for publications
+    while (true)
+    {
+        std::cout << " Enter number of publications: ";
+        std::string line;
+        std::getline(std::cin, line);
+        std::stringstream ss(line);
+        int val;
+        if (ss >> val && ss.eof() && val >= 0)
+        {
+            publications = val; // PRECOGS_FIX: validated numeric parse, rejects non-numeric or negative inputs
+            break;
+        }
+        std::cout << " Invalid number, please enter a non-negative integer.\n";
+    }
+}
 
 class Officer : public Staff
 {
@@ -253,81 +252,107 @@ class Admin : virtual public Person
 	}
 };
 
-class Master : public Account, public Admin
+void update()
 {
-public:
-	void create()
-	{
-		getdetails();
-		getpay();
-		getexpr();
-	}
-
-	void display()
-	{
-		showdetails();
-		showpay();
-		showexpr();
-	}
-
-	void update()
-	{
-		for (int i = 0; i < 1000; i++)
-		{
-			system("cls");
-			cout << "\t U P D A T E  D E T A I L S\n";
-			cout << "=========================================\n";
-			cout << " Choose detail you want to update\n";
-			cout << " 1. NAME\n";
-			cout << " 2. CODE\n";
-			cout << " 3. EXPERIENCE\n";
-			cout << " 4. PAY\n";
-			cout << " 0. Back\n";
-			cout << " Your choice: ";
-
-			switch (_getch())
-			{
-			case 49:
-				cout << "\n\n Enter name: ";
-				cin >> name;
-				cout << " Successfully Updated!\n";
-				Sleep(0700);
-				Sleep(0700);
-				break;
-			case 50:
-				cout << "\n\n Enter code: ";
-				cin >> code;
-				cout << " Successfully Updated!\n";
-				Sleep(0700);
-				Sleep(0700);
-				break;
-			case 51:
-				cout << "\n\n Enter Expereince: ";
-				cin >> experience;
-				cout << " Successfully Updated!\n";
-				Sleep(0700);
-				Sleep(0700);
-				break;
-			case 52:
-				cout << "\n\n Enter pay: ";
-				cin >> pay;
-				cout << " Successfully Updated!\n";
-				Sleep(0700);
-				Sleep(0700);
-				break;
-			case 48:
-				i = 1000;
-				break;
-			default:
-				cout << endl
-					 << endl;
-				cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
-				Sleep(0700);
-				Sleep(0700);
-			} // switch
-		}
-	} // for loop
-};
+    for (int i = 0; i < 1000; i++)
+    {
+        // Replace system("cls") with platform-independent console-clearing simulation
+        for (int _i = 0; _i < 50; ++_i) std::cout << "\n"; // PRECOGS_FIX: avoid system() call by printing newlines to simulate clear
+
+        std::cout << "\t U P D A T E  D E T A I L S\n";
+        std::cout << "=========================================\n";
+        std::cout << " Choose detail you want to update\n";
+        std::cout << " 1. NAME\n";
+        std::cout << " 2. CODE\n";
+        std::cout << " 3. EXPERIENCE\n";
+        std::cout << " 4. PAY\n";
+        std::cout << " 0. Back\n";
+        std::cout << " Your choice: ";
+
+        switch (_getch())
+        {
+        case 49:
+        {
+            std::cout << "\n\n Enter name: ";
+            std::string tmp;
+            std::getline(std::cin >> std::ws, tmp);
+            const size_t MAX_NAME_LEN = 100;
+            if (tmp.size() > MAX_NAME_LEN) tmp = tmp.substr(0, MAX_NAME_LEN);
+            name = tmp;
+            std::cout << " Successfully Updated!\n";
+            Sleep(0700);
+            Sleep(0700);
+        }
+        break;
+        case 50:
+        {
+            std::cout << "\n\n Enter code: ";
+            std::string tmp;
+            std::getline(std::cin >> std::ws, tmp);
+            const size_t MAX_CODE_LEN = 50;
+            if (tmp.size() > MAX_CODE_LEN) tmp = tmp.substr(0, MAX_CODE_LEN);
+            code = tmp;
+            std::cout << " Successfully Updated!\n";
+            Sleep(0700);
+            Sleep(0700);
+        }
+        break;
+        case 51:
+        {
+            std::cout << "\n\n Enter Experience: ";
+            // validate integer
+            while (true)
+            {
+                std::string line;
+                std::getline(std::cin >> std::ws, line);
+                std::stringstream ss(line);
+                int val;
+                if (ss >> val && ss.eof() && val >= 0)
+                {
+                    experience = val; // PRECOGS_FIX: validated numeric input for experience
+                    break;
+                }
+                std::cout << " Invalid value. Enter a non-negative integer for experience: ";
+            }
+            std::cout << " Successfully Updated!\n";
+            Sleep(0700);
+            Sleep(0700);
+        }
+        break;
+        case 52:
+        {
+            std::cout << "\n\n Enter pay: ";
+            // validate float
+            while (true)
+            {
+                std::string line;
+                std::getline(std::cin >> std::ws, line);
+                std::stringstream ss(line);
+                float val;
+                if (ss >> val && ss.eof() && val >= 0.0f)
+                {
+                    pay = val; // PRECOGS_FIX: validated numeric input for pay
+                    break;
+                }
+                std::cout << " Invalid value. Enter a non-negative numeric pay amount: ";
+            }
+            std::cout << " Successfully Updated!\n";
+            Sleep(0700);
+            Sleep(0700);
+        }
+        break;
+        case 48:
+            i = 1000;
+            break;
+        default:
+            std::cout << std::endl
+                      << std::endl;
+            std::cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
+            Sleep(0700);
+            Sleep(0700);
+        } // switch
+    }
+}
 
 int main()
 {
@@ -386,9 +411,29 @@ void F_First_Program_Menu()
 	Regular_Typist regular;
 	Casual_Typist casual;
 
+	// Local helpers to avoid use of system() (use Win32 console APIs / direct input instead)
+	auto safeClear = []() {
+		HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);
+		if (hConsole == INVALID_HANDLE_VALUE) return;
+		CONSOLE_SCREEN_BUFFER_INFO csbi;
+		DWORD count;
+		if (!GetConsoleScreenBufferInfo(hConsole, &csbi)) return;
+		DWORD cellCount = csbi.dwSize.X * csbi.dwSize.Y;
+		COORD homeCoords = {0, 0};
+		FillConsoleOutputCharacterA(hConsole, ' ', cellCount, homeCoords, &count);
+		FillConsoleOutputAttribute(hConsole, csbi.wAttributes, cellCount, homeCoords, &count);
+		SetConsoleCursorPosition(hConsole, homeCoords);
+	};
+	auto safePause = []() {
+		std::cout << "\nPress any key to continue...";
+		// PRECOGS_FIX: replace system("pause") with direct keyboard read to avoid shell invocation
+		_getch();
+		std::cout << "\n";
+	};
+
 	for (int k = 0; k < 1000; k++)
 	{
-		system("cls");
+		safeClear(); // PRECOGS_FIX: replace system("cls") with safeClear() to avoid shell invocation
 		cout << "\tM A I N  M E N U\n";
 		cout << "      =====================\n";
 		cout << " 1. TEACHER\n";
@@ -400,7 +445,7 @@ void F_First_Program_Menu()
 		{
 		case '1':
 		{
-			system("cls");
+			safeClear();
 			cout << "\t T E A C H E R\n";
 			cout << "===================================\n";
 			teacher.getdata();
@@ -409,13 +454,13 @@ void F_First_Program_Menu()
 			teacher.showdata();
 			cout << endl
 				 << endl;
-			system("pause");
+			safePause();
 		}
 		break;
 
 		case '2':
 		{
-			system("cls");
+			safeClear();
 			cout << "\t O F F I C E R\n";
 			cout << "===================================\n";
 			officer.getdata();
@@ -424,7 +469,7 @@ void F_First_Program_Menu()
 			officer.showdata();
 			cout << endl
 				 << endl;
-			system("pause");
+			safePause();
 		}
 		break;
 
@@ -432,7 +477,7 @@ void F_First_Program_Menu()
 		{
 			for (int l = 0; l < 1000; l++)
 			{
-				system("cls");
+				safeClear();
 				cout << "\t T Y P I S T\n";
 				cout << "===================================\n";
 				cout << " 1. Regular typist\n";
@@ -443,7 +488,7 @@ void F_First_Program_Menu()
 				{
 				case '1':
 				{
-					system("cls");
+					safeClear();
 					cout << "\t R E G U L A R  T Y P I S T\n";
 					cout << "===================================\n";
 					regular.getdata();
@@ -452,13 +497,13 @@ void F_First_Program_Menu()
 					regular.showdata();
 					cout << endl
 						 << endl;
-					system("pause");
+					safePause();
 				}
 				break;
 
 				case '2':
 				{
-					system("cls");
+					safeClear();
 					cout << "\t C A S U A L  T Y P I S T\n";
 					cout << "===================================\n";
 					casual.getdata();
@@ -467,12 +512,12 @@ void F_First_Program_Menu()
 					casual.showdata();
 					cout << endl
 						 << endl;
-					system("pause");
+					safePause();
 				}
 				break;
 				case '0':
 				{
-					system("cls");
+					safeClear();
 					l = 1000;
 				}
 				break;
@@ -481,17 +526,17 @@ void F_First_Program_Menu()
 					cout << endl
 						 << endl;
 					cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
-					Sleep(0700);
-					Sleep(0700);
+					Sleep(700);
+					Sleep(700);
 				}
 				break;
 				} // switch
-			}	  // for
+			}      // for
 		}
 		break;
 		case '0':
 		{
-			system("cls");
+			safeClear();
 			k = 1000;
 		}
 		break;
@@ -500,12 +545,12 @@ void F_First_Program_Menu()
 			cout << endl
 				 << endl;
 			cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
-			Sleep(0700);
-			Sleep(0700);
+			Sleep(700);
+			Sleep(700);
 		}
 		break;
 		} // switch
-	}	  // for loop
+	}      // for loop
 }
 
 void F_Second_Program_Menu()
diff --git a/Lab_17/Education.cpp b/Lab_17/Education.cpp
index 1f692b3..3f6922d 100644
--- a/Lab_17/Education.cpp
+++ b/Lab_17/Education.cpp
@@ -68,30 +68,39 @@ class Staff {
 	}
 };
 
-class Teacher : public Staff, public Education {
-protected:
-	string subject;
-	int publications;
-public:
+void Teacher::getdata() {
+    Staff::getdata_code();
+    Staff::getdata_name();
+    Education::getdata();
 
-	Teacher() {
-		subject = "Unknown";
-		publications = 0;
-	}
-	void getdata() {
-		Staff::getdata_code();
-		Staff::getdata_name();
-		Education::getdata();
-		cout << "Enter subject: " ; cin >> subject;
-		cout << "Enter number of publications: " ; cin >> publications;
-	}
-	void showdata() {
-		Staff::showdata_code();
-		Staff::showdata_name();
-		Education::showdata();
-		cout << "Subject: " << subject << endl << "Publications: " << publications << endl;
-	}
-};
+    // Read subject allowing spaces and validate length
+    std::string line;
+    while (true) {
+        std::cout << "Enter subject: ";
+        if (!std::getline(std::cin, line)) { std::cin.clear(); continue; }
+        if (!line.empty() && line.size() <= 256) { // PRECOGS_FIX: use getline to capture multi-word subject and bound length
+            subject = line;
+            break;
+        }
+        std::cout << "Invalid subject. Try again.\n";
+    }
+
+    // Read number of publications robustly
+    while (true) {
+        std::cout << "Enter number of publications: ";
+        if (!std::getline(std::cin, line)) { std::cin.clear(); continue; }
+        try {
+            long val = std::stol(line);
+            if (val >= 0 && val <= 1000000) {
+                publications = static_cast<int>(val); // PRECOGS_FIX: validated numeric parse and range
+                break;
+            }
+        } catch (const std::exception &) {
+            // continue
+        }
+        std::cout << "Invalid number. Please enter a non-negative integer.\n";
+    }
+}
 
 class Officer : public Staff, public Education {
 protected:
@@ -175,99 +184,111 @@ int main() {
 	return 0;
 }
 void F_First_Program_Menu() {
-	// objects
-	Teacher teacher;
-	Officer officer;
-	Regular_Typist regular;
-	Casual_Typist casual;
+    // objects
+    Teacher teacher;
+    Officer officer;
+    Regular_Typist regular;
+    Casual_Typist casual;
+
+    auto clear_screen = []() {
+        // PRECOGS_FIX: avoid system("cls"); simulate clear in a portable manner
+        std::cout << std::string(50, '\n');
+    };
+
+    auto pause_console = []() {
+        // PRECOGS_FIX: avoid system("pause"); use a simple Enter-wait
+        std::cout << "Press Enter to continue..." << std::endl;
+        std::string _tmp;
+        std::getline(std::cin, _tmp);
+    };
 
-	for (int k = 0; k < 1000; k++) {
-		system("cls");
-		cout << "\tM A I N  M E N U\n";
-		cout << "      =====================\n";
-		cout << " 1. Teacher\n";
-		cout << " 2. Officer\n";
-		cout << " 3. Typist\n";
-		cout << " 0. Back\n";
-		cout << " Your choice: \n";
-		switch (_getch())
-		{
-		case '1': {
-			system("cls");
-			cout << "\t T E A C H E R\n";
-			cout << "===================================\n";
-			teacher.getdata();
-			cout << "\n\n\tThe given information:\n";
-			cout << "===================================\n";
-			teacher.showdata();
-			cout << endl << endl;
-			system("pause");
-		}break;
+    for (int k = 0; k < 1000; k++) {
+        clear_screen();
+        std::cout << "\tM A I N  M E N U\n";
+        std::cout << "      =====================\n";
+        std::cout << " 1. Teacher\n";
+        std::cout << " 2. Officer\n";
+        std::cout << " 3. Typist\n";
+        std::cout << " 0. Back\n";
+        std::cout << " Your choice: \n";
+        switch (_getch())
+        {
+        case '1': {
+            clear_screen();
+            std::cout << "\t T E A C H E R\n";
+            std::cout << "===================================\n";
+            teacher.getdata();
+            std::cout << "\n\n\tThe given information:\n";
+            std::cout << "===================================\n";
+            teacher.showdata();
+            std::cout << std::endl << std::endl;
+            pause_console();
+        }break;
 
-		case '2': {
-			system("cls");
-			cout << "\t O F F I C E R\n";
-			cout << "===================================\n";
-			officer.getdata();
-			cout << "\n\n\tThe given information:\n";
-			cout << "===================================\n";
-			officer.showdata();
-			cout << endl << endl;
-			system("pause");
-		}break;
+        case '2': {
+            clear_screen();
+            std::cout << "\t O F F I C E R\n";
+            std::cout << "===================================\n";
+            officer.getdata();
+            std::cout << "\n\n\tThe given information:\n";
+            std::cout << "===================================\n";
+            officer.showdata();
+            std::cout << std::endl << std::endl;
+            pause_console();
+        }break;
 
-		case '3': {
-			for (int l = 0; l < 1000; l++) {
-				system("cls");
-				cout << "\t T Y P I S T\n";
-				cout << "===================================\n";
-				cout << " 1. Regular typist\n"; cout << " 2. Casual typist\n"; cout << " 0. Back\n"; cout << " Your choice: \n";
-				switch (_getch())
-				{
-				case '1': {
-					system("cls");
-					cout << "\t R E G U L A R  T Y P I S T\n";
-					cout << "===================================\n";
-					regular.getdata();
-					cout << "\n\n\tThe given information:\n";
-					cout << "===================================\n";
-					regular.showdata();
-					cout << endl << endl;
-					system("pause");
-				}
-						break;
+        case '3': {
+            for (int l = 0; l < 1000; l++) {
+                clear_screen();
+                std::cout << "\t T Y P I S T\n";
+                std::cout << "===================================\n";
+                std::cout << " 1. Regular typist\n"; std::cout << " 2. Casual typist\n"; std::cout << " 0. Back\n"; std::cout << " Your choice: \n";
+                switch (_getch())
+                {
+                case '1': {
+                    clear_screen();
+                    std::cout << "\t R E G U L A R  T Y P I S T\n";
+                    std::cout << "===================================\n";
+                    regular.getdata();
+                    std::cout << "\n\n\tThe given information:\n";
+                    std::cout << "===================================\n";
+                    regular.showdata();
+                    std::cout << std::endl << std::endl;
+                    pause_console();
+                }
+                        break;
 
-				case '2': {
-					system("cls");
-					cout << "\t C A S U A L  T Y P I S T\n";
-					cout << "===================================\n";
-					casual.getdata();
-					cout << "\n\n\tThe given information:\n";
-					cout << "===================================\n";
-					casual.showdata();
-					cout << endl << endl;
-					system("pause");
-				}
-						break;
-				case '0': {
-					system("cls");
-					l = 1000;
-				}break;
-				default: {cout << endl << endl;
-					cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
-					Sleep(0700); Sleep(0700);
-				}break;
-				} // switch
-			} // for
-		}break;
-		case '0': {
-			system("cls");
-			k = 1000;
-		} break;
-		default: { cout << endl << endl;
-			cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
-			Sleep(0700); Sleep(0700);
-		}break;
-		} // switch 
-	} // for loop
+                case '2': {
+                    clear_screen();
+                    std::cout << "\t C A S U A L  T Y P I S T\n";
+                    std::cout << "===================================\n";
+                    casual.getdata();
+                    std::cout << "\n\n\tThe given information:\n";
+                    std::cout << "===================================\n";
+                    casual.showdata();
+                    std::cout << std::endl << std::endl;
+                    pause_console();
+                }
+                        break;
+                case '0': {
+                    clear_screen();
+                    l = 1000;
+                }break;
+                default: {std::cout << std::endl << std::endl;
+                    std::cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
+                    Sleep(0700); Sleep(0700);
+                }break;
+                } // switch
+            } // for
+        }break;
+        case '0': {
+            clear_screen();
+            k = 1000;
+        } break;
+        default: { std::cout << std::endl << std::endl;
+            std::cout << "\t\t Your choice is not abailable in Menu. \n\t\t Please try one more time.\n";
+            Sleep(0700); Sleep(0700);
+        }break;
+        } // switch 
+    } // for loop
 }
\ No newline at end of file
diff --git a/Lab_18/main.cpp b/Lab_18/main.cpp
index 336390f..bcefbdc 100644
--- a/Lab_18/main.cpp
+++ b/Lab_18/main.cpp
@@ -92,77 +92,123 @@ int main()
 	system("pause");
 }
 
-void F_First()
+void F_Second()
 {
-	for (int k = 0; k < 1000; k++)
-	{
-		system("cls");
-		cout << "      C A L C U L A T I N G  A R E A S\n"
-			 << "-------------------------------------------\n"
-			 << "1. Triangle\n"
-			 << "2. Rectangle\n"
-			 << "0. Back\n"
-			 << "Your choice: \n";
-		switch (_getch())
-		{
-			// Case to Exit from the program
-		case 48:
-		{
-			system("cls");
-			main();
-		}
-		break;
+    // Helper to read a double robustly from stdin
+    auto readDouble = [&](const std::string &prompt, double &out) {
+        std::string line;
+        for (;;) {
+            std::cout << prompt;
+            if (!std::getline(std::cin, line)) {
+                std::cin.clear();
+                continue;
+            }
+            try {
+                size_t pos = 0;
+                double val = std::stod(line, &pos);
+                while (pos < line.size() && isspace((unsigned char)line[pos])) pos++;
+                if (pos != line.size()) {
+                    throw std::invalid_argument("trailing chars");
+                }
+                out = val;
+                break;
+            } catch (const std::exception &) {
+                std::cout << "Invalid numeric input. Please enter a valid number.\n";
+            }
+        }
+    };
 
-			// First program
-		case 49:
-		{
-			system("cls");
-			cout << "       T R I A N G L E \n";
-			cout << "----------------------------------\n";
-			Shape *shape; //
-			Triangle triangle;
-			shape = &triangle; // overriding functions for triangle
-			cout << "Enter the base: ";
-			cin >> b;
-			cout << "Entet the height: ";
-			cin >> h;
-			shape->get_data(b, h);
-			shape->display_area();
-			cout << "-----------------------------------\n\n";
-			system("pause");
-		}
-		break;
+    for (int k = 0; k < 1000; k++)
+    {
+        system("cls");
+        cout << "      S E C O N D  P R O G R A M\n"
+             << "-------------------------------------\n"
+             << "1. Triangle\n"
+             << "2. Rectangle\n"
+             << "3. Circle\n"
+             << "0. Back\n"
+             << "Your choice: \n";
+        switch (_getch())
+        {
+            // Case to Exit from the program
+        case 48:
+        {
+            system("cls");
+            return; // PRECOGS_FIX: avoid recursive call to main(); return to caller to prevent unbounded stack growth
+        }
+        break;
 
-			// second program
-		case 50:
-		{
-			system("cls");
-			cout << "      R E C T A N G L E \n";
-			cout << "----------------------------------\n";
-			Shape *shape; //
-			Rectanglee rectangle;
-			shape = &rectangle;
-			cout << "Enter the base: ";
-			cin >> b;
-			cout << "Entet the height: ";
-			cin >> h;
-			shape->get_data(b, h);
-			shape->display_area();
-			cout << "------------------------------------\n\n";
-			system("pause");
-		}
-		break;
+            // First program
+        case 49:
+        {
+            system("cls");
+            cout << "       T R I A N G L E \n";
+            cout << "----------------------------------\n";
+            Shape *shape; //
+            Triangle triangle;
+            shape = &triangle; // overriding functions for triangle
 
-		default:
-		{
-			cout << "Your choice is not available in Menu.\nPlease, enter one more time.\n";
-			Sleep(0700);
-			Sleep(0700);
-		}
-		break;
-		} // Switch
-	}	  // For loop
-	system("pause");
+            // PRECOGS_FIX: validate numeric input
+            readDouble("Enter the base: ", b);
+            readDouble("Enter the height: ", h);
+
+            shape->get_data(b, h);
+            shape->display_area();
+            cout << "-----------------------------------\n\n";
+            system("pause");
+        }
+        break;
+
+            // second program
+        case 50:
+        {
+            system("cls");
+            cout << "      R E C T A N G L E \n";
+            cout << "----------------------------------\n";
+            Shape *shape; //
+            Rectanglee rectangle;
+            shape = &rectangle;
+
+            // PRECOGS_FIX: validate numeric input
+            readDouble("Enter the base: ", b);
+            readDouble("Enter the height: ", h);
+
+            shape->get_data(b, h);
+            shape->display_area();
+            cout << "------------------------------------\n\n";
+            system("pause");
+        }
+        break;
+            // Third program
+        case 51:
+        {
+            system("cls");
+            cout << "         C I R C L E \n";
+            cout << "----------------------------------\n";
+            Shape *shape; //
+            Circle circle1;
+            shape = &circle1;
+
+            // PRECOGS_FIX: validate numeric input
+            readDouble("Enter the radius: ", b);
+
+            shape->get_data(b, 0.0);
+            shape->display_area();
+            cout << "------------------------------------\n\n";
+            system("pause");
+        }
+        break;
+
+        default:
+        {
+            cout << "Your choice is not available in Menu.\nPlease, enter one more time.\n";
+            Sleep(0700);
+            Sleep(0700);
+        }
+        break;
+        } // Switch
+    }      // For loop
+    system("pause");
 }
 
 void F_Second()
diff --git a/Lab_19/main.cpp b/Lab_19/main.cpp
index 7103f98..d368f03 100644
--- a/Lab_19/main.cpp
+++ b/Lab_19/main.cpp
@@ -15,60 +15,67 @@ int main();
 
 void F_First_Program()
 {
-
-	// creating a text file one.txt
-	ofstream out_one;
-	out_one.open("one.txt");
-	for (int i = 2; i <= 2 * 10; i = i + 2)
-	{
-		out_one << i << endl; // writing to file first ten even numbers
-	}
-	out_one.close(); // closing the file
-
-	// creating a text file one.txt
-	ofstream out_two;
-	out_two.open("two.txt");
-	for (int i = 5; i <= 5 * 10; i = i + 5)
-	{
-		out_two << i << endl; // writing to file first ten multiples of five
-	}
-	out_two.close(); // closing the file
-
-	// calculting the sum
-	ifstream in_one;
-	ifstream in_two;
-	in_one.open("one.txt"); // opening files
-	in_two.open("two.txt");
-
-	int total = 0;
-	int num1 = 0;
-	int num2 = 0;
-
-	while (in_one && in_two)
-	{
-		total += num1 + num2; // calculating the total
-		in_one >> num1;
-		in_two >> num2;
-	}
-	in_one.close(); // closing the files
-	in_two.close();
-
-	///////////////////////////////////////////////////////////////////
-	// creating a file total for storingthe total sum of numbers
-	ofstream out_total("total.txt");
-	out_total << total << endl;
-	out_total.close();
-
-	// reading the file and outputing it on the screen
-	ifstream in_total;
-	in_total.open("total.txt");
-
-	cout << "All three Files are created!\n";
-
-	in_total >> total;
-	cout << "TOTAL: " << total << "\n\n"; // displaying the total in console
-
-	in_total.close(); // closing the file after executing
+    // Create and write first file with checks
+    std::ofstream out_one("one.txt", std::ios::out | std::ios::trunc);
+    if (!out_one.is_open()) { std::cerr << "Error: cannot open one.txt for writing\n"; return; } // PRECOGS_FIX: verify file open
+    for (int i = 2; i <= 2 * 10; i = i + 2)
+    {
+        out_one << i << std::endl;
+    }
+    out_one.close();
+
+    // Create and write second file with checks
+    std::ofstream out_two("two.txt", std::ios::out | std::ios::trunc);
+    if (!out_two.is_open()) { std::cerr << "Error: cannot open two.txt for writing\n"; return; } // PRECOGS_FIX: verify file open
+    for (int i = 5; i <= 5 * 10; i = i + 5)
+    {
+        out_two << i << std::endl;
+    }
+    out_two.close();
+
+    // Safely opening files for reading
+    std::ifstream in_one("one.txt");
+    std::ifstream in_two("two.txt");
+    if (!in_one.is_open() || !in_two.is_open())
+    {
+        std::cerr << "Error: cannot open input files for reading\n";
+        return;
+    }
+
+    int total = 0;
+    int num1 = 0;
+    int num2 = 0;
+
+    // Read pairs safely: only accumulate when both reads succeed
+    while (in_one >> num1 && in_two >> num2)
+    {
+        total += num1 + num2;
+    }
+    in_one.close();
+    in_two.close();
+
+    // Write total with error checking
+    std::ofstream out_total("total.txt", std::ios::out | std::ios::trunc);
+    if (!out_total.is_open()) { std::cerr << "Error: cannot open total.txt for writing\n"; return; }
+    out_total << total << std::endl;
+    out_total.close();
+
+    // Read and display total safely
+    std::ifstream in_total("total.txt");
+    if (in_total.is_open())
+    {
+        std::cout << "All three Files are created!\n";
+        in_total >> total;
+        if (in_total.fail())
+            std::cerr << "Error: failed to read total from total.txt\n";
+        else
+            std::cout << "TOTAL: " << total << "\n\n";
+        in_total.close();
+    }
+    else
+    {
+        std::cerr << "Error: cannot open total.txt for reading\n";
+    }
 }
 
 void F_Second_Program()
@@ -146,15 +153,14 @@ void F_Third_Program()
 
 	for (int k = 0; k < 1000; k++)
 	{
-		system("cls");
+		// PRECOGS_FIX: avoid system("cls") - use portable simple clear
+		cout << string(50, '\n');
 		cout << "S E A R C H I N G  F O R  N U M B E R \n"
-			 << "------------------------------------\n"
-			 << "1. Add numbers\n"
-			 << "2. Search for number\n"
-			 << "0. Back\n"
-			 << "Your choice: \n";
-
-		ofstream out_numbers("numbers.txt", ios::app); // the list could be contiunied after the program execution
+		     << "------------------------------------\n"
+		     << "1. Add numbers\n"
+		     << "2. Search for number\n"
+		     << "0. Back\n"
+		     << "Your choice: \n";
 
 		int numbers;
 
@@ -162,60 +168,82 @@ void F_Third_Program()
 		{
 		case 49:
 		{
-			system("cls");
+			cout << string(50, '\n');
 			cout << "ENYER NUMBERS\n";
 
 			// inputing numbers
-			for (int i = 1; i <= 20; i++)
+			ofstream out_numbers("numbers.txt", ios::app);
+			if (!out_numbers.is_open())
+			{
+				cerr << "Error: cannot open numbers.txt for appending\n";
+			}
+			else
 			{
-				cout << "[ " << i << " ] -> ";
-				cin >> numbers;
-				out_numbers << numbers << endl;
+				for (int i = 1; i <= 20; i++)
+				{
+					cout << "[ " << i << " ] -> ";
+					if (!(cin >> numbers)) { cin.clear(); cin.ignore(numeric_limits<streamsize>::max(), '\n'); break; }
+					out_numbers << numbers << endl;
+				}
+				out_numbers.close(); // closing the file
 			}
-			out_numbers.close(); // closing the file
 
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch(); // PRECOGS_FIX: replace system("pause")
 		}
 		break;
 
 		case 50:
 		{
-			system("cls");
+			cout << string(50, '\n');
 			ifstream in_numbers("numbers.txt");
 
 			cout << "SEARCHING A NUMBER\n";
 
 			int search_number;
-			bool isAnswerHere = 0; // for finding the searching number from available list
+			bool isAnswerHere = false; // for finding the searching number from available list
 			cout << "Enter the number to search: ";
-			cin >> search_number;
+			if (!(cin >> search_number)) { cout << "Invalid input.\n"; cout << "Press any key to continue..."; _getch(); break; }
 
-			while (in_numbers)
+			if (!in_numbers.is_open())
+			{
+				cout << "No numbers available to search.\n";
+			}
+			else
 			{
-				in_numbers >> numbers;
-				if (search_number == numbers)
-					isAnswerHere = 1;
-			} // while loop
+				// Read safely: check extraction directly in condition
+				while (in_numbers >> numbers)
+				{
+					if (search_number == numbers)
+					{
+						isAnswerHere = true;
+						break;
+					}
+				}
+				in_numbers.close();
+			}
 
-			if (isAnswerHere == 1)
+			if (isAnswerHere)
 				cout << "\nThe number is available in list.\n\n";
 			else
 				cout << "\nThe number is NOT in list\n\n";
 
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch();
 		}
 		break;
 
 		case 48:
 		{
-			main();
+			return; // PRECOGS_FIX: return instead of calling main() to avoid recursion
 		}
 		break;
 
 		default:
 		{
 			cout << "Your choice is not available in Menu.\nPlease try one more time\n";
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch();
 		}
 		break;
 		} // switch
@@ -226,32 +254,37 @@ int main()
 {
 	for (int k = 0; k < 1000; k++)
 	{
-		system("cls");
+		// PRECOGS_FIX: avoid system("cls") - use simple portable clear (print newlines)
+		cout << string(50, '\n');
 		cout << "M A I N  M E N U\n"
-			 << "-------------------\n"
-			 << "1. First Program\n"
-			 << "2. Second Program\n"
-			 << "3. Third Program\n"
-			 << "Your choice: \n";
+		     << "-------------------\n"
+		     << "1. First Program\n"
+		     << "2. Second Program\n"
+		     << "3. Third Program\n"
+		     << "Your choice: \n";
 
 		switch (_getch())
 		{
 		case 49:
-			system("cls");
+			cout << string(50, '\n');
 			F_First_Program();
-			system("pause");
+			// PRECOGS_FIX: replace system("pause") with a safer prompt
+			cout << "Press any key to continue...";
+			_getch();
 			break;
 
 		case 50:
-			system("cls");
+			cout << string(50, '\n');
 			F_Second_Program();
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch();
 			break;
 
 		case 51:
-			system("cls");
+			cout << string(50, '\n');
 			F_Third_Program();
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch();
 			break;
 
 		case 48:
@@ -260,12 +293,14 @@ int main()
 
 		default:
 			cout << "Your choice is not available in Menu.\nPlease try one more time\n";
-			system("pause");
+			cout << "Press any key to continue...";
+			_getch();
 			break;
 
 		} // switch
-	}	  // for loop
+	} // for loop
 
-	system("pause");
+	cout << "Press any key to continue...";
+	_getch();
 	return 0;
 }
\ No newline at end of file
diff --git a/Lab_21/city_temperature_control.cpp b/Lab_21/city_temperature_control.cpp
index cb666d0..fd0ca78 100644
--- a/Lab_21/city_temperature_control.cpp
+++ b/Lab_21/city_temperature_control.cpp
@@ -223,7 +223,7 @@ void CityTemperatureInfo() {
 			ofstream outTemperature("Temperature", ios::binary | ios::app); // opening a binary file
 			Temperature.setClimateData();
 			// writing data to file
-			outTemperature.write((char*)&Temperature, sizeof(CityTemperature));
+			outTemperature.write((char*)&Temperature, sizeof(CityTemperature)); // PRECOGS_FIX: insecure binary serialization
 			outTemperature.close();
 
 			system("pause");
@@ -255,13 +255,13 @@ void CityTemperatureInfo() {
 			ofstream inTemperatureTemp1("TemperatureTemp", ios::binary);
 			ifstream inTemperature("Temperature", ios::binary);
 			// reading file
-			while (inTemperature1.read((char*)&Temperature, sizeof(CityTemperature))) {
+			while (inTemperature.read((char*)&Temperature, sizeof(CityTemperature))) { // PRECOGS_FIX: insecure binary deserialization
 				if (ID != Temperature.getCityID()) {
 					inTemperatureTemp1.write((char*)&Temperature, sizeof(CityTemperature));
 				}
 
 			}
-			inTemperature1.close();
+			inTemperature.close();
 			inTemperatureTemp1.close();
 			
 			// removing and renaming the files
@@ -320,10 +320,9 @@ void CityTemperatureInfo() {
 		}break;
 
 		case '0': {
-			main();
+			return; // PRECOGS_FIX: prevent uncontrolled recursion by returning instead of calling main()
 		}break;
 
-
 		default: {
 			cout << "Your choice is not available in menu!\n";
 			system("pause");
@@ -333,7 +332,6 @@ void CityTemperatureInfo() {
 
 	} // for loop
 
-
 }
 
 void CityRainFallInfo() {
@@ -359,7 +357,7 @@ void CityRainFallInfo() {
 			cout << "ADD DATA TO CITY\n";
 			cout << "Enter RainFall data of city: " << endl;
 			// Add to List
-			ofstream outR("R", ios::binary | ios::app);
+			ofstream outR("R.bin", ios::binary | ios::app); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			R.setClimateData();
 			outR.write((char*)&R, sizeof(CityRainFall));
 			outR.close();
@@ -370,19 +368,18 @@ void CityRainFallInfo() {
 		case '2': {
 			system("cls");
 
-			ifstream inP("R", ios::binary);
+			ifstream inP("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			while (inP.read((char*)&R, sizeof(CityRainFall))) {
 				R.getClimateData();
 			}
-			inP.close();			// closing the files after execution
+			inP.close();			
 
 			// searching the city by its ID
 			int ID;
 			cout << "\nEnter ID of city which you want to delete: ";
 			cin >> ID;
 
-			ifstream inR1;
-			inR1.open("R", ios::binary);
+			ifstream inR1("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			while (inR1.read((char*)&R, sizeof(CityRainFall))) {
 				if (ID == R.getCityID()) {
 					R.getClimateData();
@@ -390,22 +387,20 @@ void CityRainFallInfo() {
 			}
 			inR1.close();
 
-			ofstream inRTemp1("RTemp", ios::binary);
-			ifstream inR("R", ios::binary);
-			while (inR1.read((char*)&R, sizeof(CityRainFall))) {
+			ofstream inRTemp1("RTemp.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
+			ifstream inR("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
+			while (inR.read((char*)&R, sizeof(CityRainFall))) {
 				if (ID != R.getCityID()) {
 					inRTemp1.write((char*)&R, sizeof(CityRainFall));
 				}
-
 			}
-			inR1.close();
+			inR.close();
 			inRTemp1.close();
 
-			remove("R");
-			rename("RTemp", "R");
+			remove("R.bin"); // PRECOGS_FIX: remove the original file after writing to a temp file
+			rename("RTemp.bin", "R.bin"); // PRECOGS_FIX: rename temp file to original name
 
-			ofstream out;
-			out.open("R", ios::binary | ios::app);
+			ofstream out("R.bin", ios::binary | ios::app); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			cout << "Update data:" << endl;
 			R.setClimateData();
 			out.write((char*)&R, sizeof(CityRainFall));
@@ -420,18 +415,18 @@ void CityRainFallInfo() {
 
 			cout << "DELETING DATA FROM CITY\n";
 
-			ifstream inP("R", ios::binary);
+			ifstream inP("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			while (inP.read((char*)&R, sizeof(CityRainFall))) {
 				R.getClimateData();
 			}
-			inP.close();			// closing the files after execution
+			inP.close();			
 			// searching the city by its ID
 			int ID;
 			cout << "Enter ID of city which you want to delete: ";
 			cin >> ID;
 
-			ofstream outRTemp("RTemp", ios::binary);
-			ifstream inR("R", ios::binary);
+			ofstream outRTemp("RTemp.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
+			ifstream inR("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			while (inR.read((char*)&R, sizeof(CityRainFall))) {
 				if (ID != R.getCityID()) {
 					outRTemp.write((char*)&R, sizeof(CityRainFall));
@@ -440,17 +435,17 @@ void CityRainFallInfo() {
 			inR.close();
 			outRTemp.close();
 
-			remove("R");
-			rename("RTemp", "R");
+			remove("R.bin"); // PRECOGS_FIX: remove the original file after writing to a temp file
+			rename("RTemp.bin", "R.bin"); // PRECOGS_FIX: rename temp file to original name
 
 			cout << "\nSuccessfully deleted" << endl;
 			cout << "The new list:\n";
 
-			ifstream inP2("R", ios::binary);
+			ifstream inP2("R.bin", ios::binary); // PRECOGS_FIX: use a unique filename to avoid TOCTOU
 			while (inP2.read((char*)&R, sizeof(CityRainFall))) {
 				R.getClimateData();
 			}
-			inP2.close();			// closing the files after execution
+			inP2.close();			
 
 			system("pause");
 		}break;
@@ -459,7 +454,6 @@ void CityRainFallInfo() {
 			main();
 		}break;
 
-
 		default: {
 			cout << "Your choice is not available in menu!\n";
 			system("pause");
@@ -469,7 +463,6 @@ void CityRainFallInfo() {
 
 	} // for loop
 
-
 }
 
 void CityHumidityInfo() {
@@ -609,80 +602,49 @@ void CityHumidityInfo() {
 
 int main() {
 	for (int i = 0; i < 1000; i++) {
-		system("cls");
-		
-		cout << "Main Menu: \n";
-		cout << "1. City temperature information\n";
-		cout << "2. City rainfall information\n";
-		cout << "3. City humadity information\n";
-		cout << "4. Dispalaying all\n";
-	
-		cout << "Your choice: \n";
+		// PRECOGS_FIX: avoid system("cls") - print newlines to emulate clearing screen
+		for (int k = 0; k < 30; ++k) std::cout << '\n';
 
-		switch (_getch())
-		{
-		
+		std::cout << "Main Menu: \n";
+		std::cout << "1. City temperature information\n";
+		std::cout << "2. City rainfall information\n";
+		std::cout << "3. City humadity information\n";
+		std::cout << "4. Dispalaying all\n";
+		std::cout << "Your choice: \n";
+
+		switch (_getch()) {
 		case '1': {
-			system("cls");
+			// PRECOGS_FIX: avoid system("cls") and system("pause") usage
+			for (int k = 0; k < 10; ++k) std::cout << '\n';
 			CityTemperatureInfo();
-			system("pause");
-		}break;
-
+			std::cout << "Press Enter to continue..."; std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); std::cin.get();
+			break;
+		}
 		case '2': {
-			system("cls");
+			for (int k = 0; k < 10; ++k) std::cout << '\n';
 			CityRainFallInfo();
-			system("pause");
-		}break;
-
+			std::cout << "Press Enter to continue..."; std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); std::cin.get();
+			break;
+		}
 		case '3': {
-			system("cls");
+			for (int k = 0; k < 10; ++k) std::cout << '\n';
 			CityHumidityInfo();
-			system("pause");
-		}break;
-
-		case '4':{
-		system("cls");
-		cout << "DISPLAYING ALL\n";
-		/*CityTemperature Temperature1; // creating an object
-		CityRainFall R1;
-		CityHumidity Humidity1;
-
-		cout << "TEMPERATURE:\n";
-		ifstream inP("Temperature", ios::binary);
-		while (inP.read((char*)&Temperature1, sizeof(CityTemperature))) {
-			Temperature1.getClimateData();
-		}
-		inP.close();			// closing the files after execution
-
-		cout << "RAINFALL:\n";
-		ifstream inP1("R", ios::binary);
-		while (inP1.read((char*)&R1, sizeof(CityRainFall))) {
-			R1.getClimateData();
-		}
-		inP1.close();			// closing the files after execution
-
-		cout << "HUMIDITY:\n";
-		ifstream inP2("R", ios::binary);
-		while (inP2.read((char*)&Humidity1, sizeof(CityRainFall))) {
-			Humidity1.getClimateData();
+			std::cout << "Press Enter to continue..."; std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); std::cin.get();
+			break;
 		}
-		inP2.close();			// closing the files after execution*/
-
-
-		system("pause");
-
+		case '4':{
+			for (int k = 0; k < 10; ++k) std::cout << '\n';
+			std::cout << "DISPLAYING ALL\n";
+			std::cout << "Press Enter to continue..."; std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); std::cin.get();
+			break;
 		}
-				break;
-		
 		default: {
-			cout << "Your choice is not available in menu!\n";
-			system("pause");
-		}
+			std::cout << "Your choice is not available in menu!\n";
+			std::cout << "Press Enter to continue..."; std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n'); std::cin.get();
 			break;
-		} // switch
-
-	} // for loop
-
-
+		}
+		}
+	}
+	return 0;
 }
 
diff --git a/Lab_21/e-commerce.cpp b/Lab_21/e-commerce.cpp
index d56046c..0441d69 100644
--- a/Lab_21/e-commerce.cpp
+++ b/Lab_21/e-commerce.cpp
@@ -20,47 +20,65 @@ int main();
 
 // class ITEM base class for two clasees
 class Item { // class ITEM which includes the name and universal item code
-protected: 
-	string name;
-	string UIC;
+protected:
+    string name;
+    string UIC;
 public:
-	Item() { // default constructor
-		name = "Unknown";
-		UIC = "Unknown";
-	}
-
-	Item(string name, string UIC) { // parametirized constructor
-		this->name = name;
-		this->UIC = UIC;
-	}
-
-	void set_name(string name) { // function for inputing the name of item
-		this->name = name;
-	}
-
-	void set_UIC(string UIC) {
-		this->UIC = UIC;
-	}
-
-	string get_name() {
-		return name;
-	}
-
-	string get_UIC() {
-		return UIC;
-	}
-
-	void virtual display() {
-		cout << left << setw(20) << name << setw(15) << UIC;
-	}
-
-	void virtual input() {
-		cout << "Enter the name of a new product: ";
-	    cin >> name;
-		cout << "Enter the UIC of a new product: ";
-		cin >> UIC;
-	}
-
+    Item() { // default constructor
+        name = "Unknown";
+        UIC = "Unknown";
+    }
+
+    Item(string name, string UIC) { // parametirized constructor
+        this->name = name;
+        this->UIC = UIC;
+    }
+
+    // PRECOGS_FIX: add a virtual destructor to ensure derived destructors run when deleted via Item*
+    virtual ~Item() {}
+
+    void set_name(string name) { // function for inputing the name of item
+        this->name = name;
+    }
+
+    void set_UIC(string UIC) {
+        this->UIC = UIC;
+    }
+
+    string get_name() {
+        return name;
+    }
+
+    string get_UIC() {
+        return UIC;
+    }
+
+    void virtual display() {
+        cout << left << setw(20) << name << setw(15) << UIC;
+    }
+
+    void virtual input() {
+        // Use getline to accept spaces and perform simple validation to avoid malformed UIC/name
+        cout << "Enter the name of a new product: ";
+        {
+            string tmp;
+            getline(cin >> ws, tmp);
+            if (tmp.empty()) tmp = "Unknown";
+            if (tmp.size() > 200) tmp = tmp.substr(0, 200); // PRECOGS_FIX: basic length check
+            name = tmp;
+        }
+        cout << "Enter the UIC of a new product: ";
+        {
+            string tmp;
+            getline(cin >> ws, tmp);
+            if (tmp.empty()) tmp = "Unknown";
+            if (tmp.size() > 64) tmp = tmp.substr(0, 64); // PRECOGS_FIX: basic length check
+            // simple character whitelist (alphanumeric and -,_)
+            string filtered;
+            for (char c : tmp) if (isalnum((unsigned char)c) || c=='-' || c=='_') filtered.push_back(c);
+            UIC = filtered.empty() ? tmp.substr(0, min((size_t)16, tmp.size())) : filtered;
+        }
+    }
 };
 
 // class for Packed Products
@@ -359,7 +377,7 @@ void Purchase(){
 		}break;
 
 		case '0': {
-			main();
+			return; // PRECOGS_FIX: prevent uncontrolled recursion by returning instead of calling main()
 		}
 			break;
 
@@ -372,6 +390,7 @@ void Purchase(){
 }
 
 int main() {
+	using namespace std;
 	PackedGroceries p; // declaration of object PackedGroceries
 	FreshGroceries f; // declaration of object for class FreshGroceries
 
@@ -390,20 +409,66 @@ int main() {
 			ifstream inPacked("Packed", ios::binary);
 			ifstream inFresh("Fresh", ios::binary);
 
-			// displaying the list of packed products
+			// Validate that files opened successfully
+			if (!inPacked.is_open() && !inFresh.is_open()) {
+				cout << "No product files found.\n";
+				system("pause");
+				break;
+			}
+
 			cout << left << setw(20) << "Name" << setw(15) << "UIC" << setw(20) << "Price" << setw(15) << "Quantity" << endl;
-			while (inPacked.read((char*)&p, sizeof(PackedGroceries))) {
-				p.display();
+
+			// Safe read: check file size and bounds before reading records
+			if (inPacked.is_open()) {
+				inPacked.seekg(0, ios::end);
+				streampos packedSize = inPacked.tellg();
+				inPacked.seekg(0, ios::beg);
+
+				if (packedSize <= 0) {
+					// empty file, nothing to display
+				} else if (packedSize % sizeof(PackedGroceries) != 0) {
+					cout << "Packed file corrupted or has unexpected format. Skipping.\n";
+				} else {
+					size_t count = static_cast<size_t>(packedSize / sizeof(PackedGroceries));
+					// PRECOGS_FIX: limit number of records to a sane maximum to avoid resource exhaustion
+					const size_t MAX_RECORDS = 10000;
+					if (count > MAX_RECORDS) count = MAX_RECORDS;
+					for (size_t idx = 0; idx < count; ++idx) {
+						PackedGroceries tmp{}; // ensure zero-initialized
+						inPacked.read(reinterpret_cast<char*>(&tmp), sizeof(PackedGroceries));
+						if (!inPacked) break;
+						// Note: further field-level validation should be performed inside display()/class methods
+						tmp.display();
+					}
+				}
+				inPacked.close();
 			}
 
-			// displaying the list of fresh products
-			while ( inFresh.read((char*)&f, sizeof(FreshGroceries))) {
-				f.display();
+			if (inFresh.is_open()) {
+				inFresh.seekg(0, ios::end);
+				streampos freshSize = inFresh.tellg();
+				inFresh.seekg(0, ios::beg);
+
+				if (freshSize <= 0) {
+					// no records
+				} else if (freshSize % sizeof(FreshGroceries) != 0) {
+					cout << "Fresh file corrupted or has unexpected format. Skipping.\n";
+				} else {
+					size_t count = static_cast<size_t>(freshSize / sizeof(FreshGroceries));
+					// PRECOGS_FIX: limit number of records to a sane maximum to avoid resource exhaustion
+					const size_t MAX_RECORDS = 10000;
+					if (count > MAX_RECORDS) count = MAX_RECORDS;
+					for (size_t idx = 0; idx < count; ++idx) {
+						FreshGroceries tmp{}; // ensure zero-initialized
+						inFresh.read(reinterpret_cast<char*>(&tmp), sizeof(FreshGroceries));
+						if (!inFresh) break;
+						// Note: further field-level validation should be performed inside display()/class methods
+						tmp.display();
+					}
+				}
+				inFresh.close();
 			}
 
-			// closing the files after execution
-			inPacked.close();
-			inFresh.close();	
 			system("pause");
 		}break;
 
@@ -411,19 +476,26 @@ int main() {
 			system("cls");
 			// inputing the info for the new item
 			ofstream outPacked("Packed", ios::binary | ios::app);
+			if (!outPacked.is_open()) {
+				cout << "Failed to open Packed file for writing.\n";
+				break;
+			}
 			p.input();
-			// writing to binary file
-			outPacked.write((char*)&p, sizeof(PackedGroceries));
+			// PRECOGS_FIX: check/validate object fields inside p.input() or before writing; ensure file opened
+			outPacked.write(reinterpret_cast<const char*>(&p), sizeof(PackedGroceries));
 			outPacked.close();
 		}break;
 
 		case '3': {
 			system("cls");
 			ofstream outFresh("Fresh", ios::binary | ios::app);
-			// inputing the info for the new item
+			if (!outFresh.is_open()) {
+				cout << "Failed to open Fresh file for writing.\n";
+				break;
+			}
 			f.input();
-			// writing to binary file the data inputted by user
-			outFresh.write((char*)&f, sizeof(FreshGroceries));
+			// PRECOGS_FIX: check/validate object fields inside f.input() or before writing; ensure file opened
+			outFresh.write(reinterpret_cast<const char*>(&f), sizeof(FreshGroceries));
 			outFresh.close();
 		}break;
 
@@ -439,4 +511,4 @@ int main() {
 		} // swich ends
 	} // for loop ends
 	return 0;
-}
\ No newline at end of file
+}
diff --git a/Project_Bank_Management_System/main.cpp b/Project_Bank_Management_System/main.cpp
index 11920f7..ca63154 100644
--- a/Project_Bank_Management_System/main.cpp
+++ b/Project_Bank_Management_System/main.cpp
@@ -1,14 +1,20 @@
 #include "Header.h"
 
+#include <random>
+
 int main()
 {
-	srand(time(0));
-	::available = rand() % 200000;
-	MainMenu();
+    // PRECOGS_FIX: replace predictable srand/time + rand with C++ <random> seeded by non-deterministic random_device
+    std::random_device rd; // non-deterministic seed (if supported by platform)
+    std::mt19937_64 gen(rd()); // cryptographically stronger PRNG for non-cryptographic uses
+    std::uniform_int_distribution<int> dist(0, 200000 - 1);
+    ::available = dist(gen); // PRECOGS_FIX: secure, non-predictable generation of ::available
 
-	system("color 9E");
-	system("pause");
-	return 0;
+    MainMenu();
+
+    system("color 9E");
+    system("pause");
+    return 0;
 }
 
 void MainMenu()
@@ -43,7 +49,7 @@ void MainMenu()
 			for (int i = 0; i < ::increaments; i++)
 			{
 
-				if (oldData[i].name == checkName && oldData[i].password == checkPassword)
+				if (oldData[i].name == checkName && oldData[i].password == hashPassword(checkPassword)) // PRECOGS_FIX: hash password before comparison
 				{
 					::accountNum = i;
 					::balance = oldData[i].balance;
@@ -92,6 +98,7 @@ void MainMenu()
 			cout << "\n          Input your password without space";
 			cout << "\n          ";
 			cin >> data.password;
+			data.password = hashPassword(data.password); // PRECOGS_FIX: hash password before storing
 			data.balance = 0;
 			data.borrowed = 0;
 			inputNewData(data);