using System;

using System.Threading;

using System.Threading.Tasks;

using System.Diagnostics;

​

public static class Program

{

    public static async Task Main()

    {

        var stopwatch = Stopwatch.StartNew();

        await using (new Timer(_ => Thread.Sleep(1000), null, 0, Timeout.Infinite))

        {

            Thread.Sleep(100);

        }

        Console.WriteLine($"Duration: {stopwatch.ElapsedMilliseconds:#,0} msec");

    }

}