Asynchronouse patterns in C#

AsyncPatterns.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AsyncPatterns
{
    class Program
    {
        static void Main(string[] args)
        {
            DoSerial().Wait();
        }

        private static void DoParallelAll()
        {
            var start = Environment.TickCount;
            var tasks = new Task<int>[3];
            tasks[0] = GetSlowIntTask(1);
            tasks[1] = GetSlowIntTask(2);
            tasks[2] = GetSlowIntTask(3);
            Task.WaitAll(tasks);
            for (int i = 0; i < 3; i++)
            {
                Console.Out.WriteLine(" Time: " + (Environment.TickCount - start));
                Console.Out.WriteLine("Res " + i + ": " + tasks[i].Result);
            }
        }

        private static void DoParallelFirst()
        {
            var start = Environment.TickCount;
            var tasks = new Task<int>[3];
            tasks[0] = GetSlowIntTask(1);
            tasks[1] = GetSlowIntTask(2);
            tasks[2] = GetSlowIntTask(3);
            int firstResult = Task.WaitAny(tasks);
            Console.Out.WriteLine(" Time: " + (Environment.TickCount - start));
            Console.Out.WriteLine("Res " + firstResult);
        }

        private static async Task DoSerial()
        {
            var start = Environment.TickCount;
            var tasks = new Task<int>[3];
            var str = await GetSlowStringTask("Hello world");
            var len = await GetSlowIntTask(str.Length);
            var res = await GetSlowStringTask("Len: " + len);
            Console.Out.WriteLine(" Time: " + (Environment.TickCount - start));
            Console.Out.WriteLine(res);
        }

        public static async Task<string> GetSlowStringTask(String toReturn)
        {
            await Task.Delay(250);
            return toReturn;
        }

        public static async Task<int> GetSlowIntTask(int toReturn)
        {
            await Task.Delay(250);
            return toReturn;
        }
    }
}