using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Runtime.Serialization.Formatters.Binary;

using System.Text;

using System.Threading;

using System.Xml.Serialization;

​

namespace DemoCG

{

    class Program

    {

        static Object obj = new object();

        static int counter = 0;

        static void Main(string[] args)

        {

            Thread t1 = new Thread(Print1);

            Thread t2 = new Thread(Print1);

​

            t1.Start();

            t2.Start();

​

            t1.Join();

            t2.Join();

​

            Console.WriteLine("Done");

            Console.WriteLine(counter);

        }

        static void Print1()

        {

            for (int i = 0; i < 1000000; i++)

            {

                lock (obj)

                {

                    counter++;                              // 1870 - 2000 

                }

            }

        }

    }

}

​