using System;

using System.Threading;

using System.Threading.Tasks;

using System.Collections.Generic;

public class Program

{

    public static async Task Main()

    {

        await new Program().Run();

    }

    public async Task Run()

    {

        var rand = new Random();

        var tasks = new List<Task>();

        for(var counter = 1; counter < 5; counter++)

        {

            tasks.Add(PerformTask(counter, rand.Next(0, 2000)));

        }

        await Task.WhenAll(tasks);

    }

    public async Task PerformTask(int taskNumber, int timeout)

    {

        Console.WriteLine(string.Format("Starting task {0}", taskNumber));

        System.Threading.Thread.Sleep(timeout);

        Console.WriteLine(string.Format("Task {0} finished in {1} milliseconds", taskNumber, timeout));

    }

}