class Program
    {
        static void Main(string[] args)
        {
            Thread t1 = new Thread(ThreadProc);
            Thread t2 = new Thread(ThreadProc);
            Thread t3 = new Thread(ThreadProc);
            t1.Start();
            t2.Start();
            t3.Start();

            t1.Join();
            t2.Join();
            t3.Join();
        }

        public static object sync1 = new object();
        public static object sync2 = new object();
        public static void ThreadProc()
        {            
            if (Monitor.TryEnter(sync1))
            {
                try
                {
                    DoSmth();
                    lock (sync2)
                    {
                        Monitor.PulseAll(sync2);
                    }
                }
                finally
                {
                    Monitor.Exit(sync1);
                }

            }
            else
            {
                lock (sync2)
                {
                    Monitor.Wait(sync2);
                }
            }
        }

        public static void DoSmth()
        {
            Console.WriteLine("i'm here");
        }
    }