using System;

public class Program

{

    public static void Main()

    {

        string userChoice = string.Empty;

        do

        {

            Console.WriteLine("Please Enrter Your Target ?");

            int userT = int.Parse(Console.ReadLine());

            int start = 0;

​

            while(start <= userT){

                Console.Write(start + " ");

                start = start + 2;

            }

​

            do

            {

                Console.WriteLine("Do you want to Continue, Please Enter Y or N ?");

                userChoice = Console.ReadLine().ToUpper();

                if(userChoice != "Y" && userChoice != "N")

                    Console.WriteLine("Please Enter Y or N ?"); 

            }while(userChoice != "Y" && userChoice != "N");         

        }while(userChoice == "Y");

​

    }

}