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

namespace ConsoleApplication3
{
    class Program
    {
        private static   readonly  object _lockObject = new  object();
        private static int _number = 0 ;

        static void Main( string[] args )
        {
            //for (int i = 0; i < 10; i++)
            //{
            //    new Thread(() =>
            //        {
            //            for (int j = 0; j < 3; )
            //            {
            //                Monitor.Enter(_lockObject);
            //                Console.WriteLine(_number);
            //                _number++;
            //                Monitor.Exit(_lockObject);
            //                j++;
            //            }

            //        }).Start();

            //}
            Thread thead1 = new Thread(Run1);
            Thread thead2 = new Thread(Run2);
            Thread thead3 = new Thread(Run3);

            thead1.Start ();
            thead2.Start ();
            thead3.Start ();

        }

        private static void Run1()
        {
            for (int i = 0; i < 10; )
            {
                Monitor. Enter(_lockObject );
                if (_number % 3 == 0)
                {
                    Console. WriteLine("a" );
                    _number++;
                    i++;

                }
                Monitor. Exit(_lockObject );
            }

        }

        private static void Run2()
        {
            for (int i = 0; i < 10; )
            {
                Monitor. Enter(_lockObject );
                if (_number % 3 == 1)
                {
                    Console. WriteLine("b" );
                    _number++;
                    i++;

                }
                Monitor. Exit(_lockObject );
            }
        }

        private static void Run3()
        {
            for (int i = 0; i < 10;  )
            {
                Monitor. Enter(_lockObject );
                if (_number % 3 == 2)
                {
                    Console. WriteLine("c" );
                    _number++;
                    i++;

                }
                Monitor. Exit(_lockObject );
            }
        }

    }
}