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

namespace InterlockedExample
{
    class Program
    {
        public static object syncObject;
        public static int x;
        public static int y;

        static void SwapXY()
        {
            lock (syncObject)
            {
                int z = x;

                x = y;

                #region Some potentially time consuming operation
                for (int i = 0; i < int.MaxValue / 20; i++)
                    ;
                #endregion

                y = z;
            }
        }

        static void Main(string[] args)
        {
            syncObject = new object();
            for (int i = 1; i < 1000; i++)
            {
                x = 1;
                y = 0;
                Thread one = new Thread(SwapXY);
                Thread two = new Thread(SwapXY);

                one.Start();
                two.Start();

                one.Join();
                two.Join();

                if (x != 1 || y != 0)
                {
                    Console.WriteLine("Incorrect swap on try {0}", i);
                }
                else
                {
                    Console.WriteLine(i);
                }
            }
        }
    }
}