using System;

using System.Threading;

​

public class Program

{

    public static void Main()

    {

        TimeSpan tp = new TimeSpan(0, 0,5);

        Console.WriteLine("START"); 

        while(tp.TotalSeconds > 0)

        {

            Console.WriteLine(tp.ToString("hh\\:mm\\:ss"));

            tp = tp - TimeSpan.FromSeconds(1);

            //Thread.Sleep(1000); //Estoura o tempo limite do fiddle

        }

        Console.WriteLine(tp.ToString("hh\\:mm\\:ss"));

        Console.WriteLine("FIM");   

    }

}

​

​