using System.Diagnostics;

using System;

using System.Threading.Tasks;

public class Program

{

        public static void Main(string[] args)

        {

            try

            {

                var stp = new Stopwatch();

                stp.Start();

                DoSomething().Wait();

​

                stp.Stop();

                Console.WriteLine("Total time to " + stp.Elapsed);

            }

            finally

            {

                Console.WriteLine("All task executed");

​

            }

        }

​

​

        private static Task DoSomething()

        {

            var t1 = DoSomething2();

            var t2 = DoSomething3();

            return Task.WhenAll(t1, t2);

        }

​

        private static Task DoSomething2()

        {

            Console.WriteLine("DoSomethign 2");

            return Task.Delay(3000);

        }

​

        private static Task DoSomething3()

        {

            Console.WriteLine("DoSomethign 3");

            return Task.Delay(3000);

        }

}