Untitled

using System;
using System.Threading;

class Program
{
    static void Main(string[] args)
    {
        int n = 15;
        AutoResetEvent t1Event = new AutoResetEvent(false);
        AutoResetEvent t2Event = new AutoResetEvent(false);
        AutoResetEvent t3Event = new AutoResetEvent(false);
        Thread t1 = new Thread(() =>
        {
            for (int i = 1; i <= n; i += 3)
            {
                Console.WriteLine("Thread 1: " + i);
                t2Event.Set();
                t1Event.WaitOne();
            }
        });
        Thread t2 = new Thread(() =>
        {
            for (int i = 2; i <= n; i += 3)
            {
                t2Event.WaitOne();
                Console.WriteLine("Thread 2: " + i);
                t3Event.Set();
            }
        });
        Thread t3 = new Thread(() =>
        {
            for (int i = 3; i <= n; i += 3)
            {
                t3Event.WaitOne();
                Console.WriteLine("Thread 3: " + i);
                t1Event.Set();
            }
        });
        t1.Start();
        t2.Start();
        t3.Start();
        Console.ReadKey();
    }
}