using System;

public class Program

{

    public static void Main()

    {

            string input;

            string answer;

            int inputNumber;

            double tuition;

            double payment;

            do

            {

                Console.Clear();

                Console.WriteLine("Tuition Program");

                Console.Write("Enter tuition: ");

                input = Console.ReadLine();

                if (Int32.TryParse(input, out inputNumber) == true)

                {

                    if (inputNumber >= 5000)

                    {

                        tuition = (double.Parse(input));

                        Console.WriteLine("Please select an option here: ");

                        Console.WriteLine("[1] Full Payment - 20% discount");

                        Console.WriteLine("[2] Installment A - 5% interest");

                        Console.WriteLine("[3] Installment B - 10% interest");

                        Console.Write("Enter an option: ");

                        input = Console.ReadLine();

                        if (Int32.TryParse(input, out inputNumber) == true)

                        {

                            inputNumber = (Int32.Parse(input));

                            switch (inputNumber)

                            {

                                case 1:

                                        payment = tuition * .80;

                                        Console.WriteLine("Your TOTAL payment in your tuition is {0:0,0.00} ", payment);

                                    break;

                                case 2:

                                       payment = tuition * 1.05;

                                       Console.WriteLine("Your TOTAL payment in your tuition is {0:0,0.00} ", payment);

                                    break;

                                case 3:

                                       payment = tuition * 1.10;

                                       Console.WriteLine("Your TOTAL payment in your tuition is {0:0,0.00} ", payment);

                                    break;

                            }

                        }

                        else

                        {

                            Console.WriteLine("You type invalid number or character Please try again.");

                        }

                    }

                    else

                    {

                        Console.WriteLine("Your amount is too low. Please try again");

                    }

                }

                else

                {

                    Console.WriteLine("Invalid input. Please enter a number.");

                }

                Console.Write("Do you want to try again? [Y/y]: ");

                answer = Console.ReadLine();

            }

            while ((answer == "Y") || (answer == "y"));

            Console.WriteLine("End of the program. Press any key to exit.");

        }

    }

​