static void Main(string[] args)
        {
star:
            Console.Clear();
            Console.WriteLine("\t=================================================================================");
            Console.WriteLine("\t\t\t\tWelcome to library system.");

            Console.WriteLine("\t\t\t\tTo entry student information enter: 1");
            Console.WriteLine("\t\t\t\tTo entry book information enter: 2");
            Console.WriteLine("\t\t\t\tTo issue a book, enter: 3");
            Console.WriteLine("\t\t\t\tTo return a book enter: 4");
            Console.WriteLine("\t\t\t\tTo check fine, enter: 5 ");
            Console.WriteLine("\t\t\t\tTo receive fine, enter: 6");
            Console.WriteLine("\t=================================================================================");

            try
            {
                Console.Write("\n\n\nPlease enter your choice: ");
                int ch = int.Parse(Console.ReadLine());


                Console.WriteLine("=================================");


                switch (ch)
                {
                case 1:
                    EntryStudent entryStudent = new EntryStudent();
                    entryStudent.studentEntry();
                    break;

                case 2:

                    BookEntry bookEntry = new BookEntry();
                    bookEntry.EntryBook();
                    break;

                case 3:
                    BookIssue bookIssue = new BookIssue();
                    bookIssue.IssueBookToStudent();
                    break;

                case 4:
                    BookReturn bookReturn = new BookReturn();
                    bookReturn.ReturnBookInfo();
                    break;

                case 5:
                    CheckFine checkFine = new CheckFine();
                    checkFine.CheckStudentFine();
                    break;

                case 6:
                    ReceiveFine receiveFine = new ReceiveFine();
                    receiveFine.FineReceive();
                    break;


                default:
                    Console.WriteLine("Invalid Key Given.Please Try Again");
                    break;
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);

                Console.Beep(400, 1500);

                goto star;
            }
        }