using System;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        Task.Factory.StartNew(Handle);

    }

    public static void Handle(){

        Console.WriteLine(Thread.CurrentThread.ManagedThreadId);

        var tcs = new TaskCompletionSource<bool>();

        Task.Run(() => {

            Console.WriteLine(Thread.CurrentThread.ManagedThreadId);

            Thread.Sleep(1000);

            tcs.SetResult(true);

        });

        tcs.Task.Wait();

    }

}