using System;

using System.Threading.Tasks;

using System.Threading;

using System.Collections.Generic;

public class Program

{

    static int stopAt = 10;

    static int stopCount = 0;

    public static async Task SpawnInitialTasks()

    {

        IList<Task> tasks = new List<Task>();

        for (int i = 1; i < 4; i++)

        {

            tasks.Add(RunNextTask(500 / i, i));

        }

        foreach (var task in tasks) {

            await task; 

        }

    }

    public static async Task RunNextTask(int delay, int taskNumber)

    {

        for(int i = 1; i <= 10; i++) {

            await Task.Delay(delay);

            Console.WriteLine(taskNumber + ": " + i); 

        }

    }

    public static void Main(string[] args)

    {

        SpawnInitialTasks().Wait();

    }

}