using System;

public class Program

{

    public static void Main()

    {

        int num;

        bool isNum;

        do

        {

            Console.WriteLine("Enter a value: \n Press -1 to exit.");

            isNum = int.TryParse(Console.ReadLine(), out num);

            if(!isNum)

            {

                Console.WriteLine("You have entered an incorrect value.");

            }

            else

                if(num != -1)

                {

                    Console.WriteLine("You have entered:" + num);

                }

                else

                    Console.WriteLine("Program has ended.");

        }

        while(num != -1);

    }

}