using System;

using System.Threading.Tasks;

using System.Linq;

​

public class Program

{

    public static async Task Main()

    {

        Console.WriteLine("Hello World");

        var users = Enumerable.Range(1, 10);

        var tasks1 = users.Select(user => Task.Delay(1000));

        await Task.WhenAll(tasks1);

        var tasks2 = users.Select(async user => await Task.Delay(1000));

        await Task.WhenAll(tasks2);

        Console.WriteLine("Finished");

    }

}