using System;

using System.Threading;

using System.Threading.Tasks;

​

public class Program

{

    public static void Main()

    {

        var console = new object();

        int i = 0;

        Task.Run(() =>

        {

            lock(console)

                while(i++ < 10)

                {

                    Console.Write(i);

                    Monitor.Pulse(console);

                    Monitor.Wait(console);

                }

        });

        Task.Run(() =>

        {

            lock(console)

                while(i < 10)

                {

                    Console.Write('+');

                    Monitor.Pulse(console);

                    Monitor.Wait(console);

                }

        });

    }

}