static void MainMenu()
        {
            char choice;

            // Main menu

            Console.WriteLine("Press [1] to Login as Admin");
            Console.WriteLine("Press [2] to Login as Student");
            choice = char.Parse(Console.ReadLine());

            if (choice !='1' && choice != '2')
            {
                Console.WriteLine("Invalid Choice");

                    MainMenu();
            }

             else {

                switch (choice)
                {
                    //Admin menu
                    case '1':
                        Console.WriteLine("Please Enter the Admin name : ");
                        string adminName = Console.ReadLine();
                        Console.WriteLine("Please Enter the Password : ");
                        string adminPassword = Console.ReadLine();


                        if (LoginAdmin(adminName, adminPassword))
                        {
                            AdminMenu();

                        }
                        else
                        {
                            Console.WriteLine("Invalid Username or Password !");
                        }
}
}