// When the program finishes running

using System;

using System.Threading;

​

public class Program

{

    private static object _a = new object();

    private static object _b = new object();

    public static void Main()

    {

        var thread1 = new Thread(Thread1);

        thread1.Start();

        var thread2 = new Thread(Thread2);

        thread2.Start();

        Console.WriteLine("Hello!");

    }

    private static void Thread1() {

        lock(_a) {

            Thread.Sleep(200);

            lock(_b) {

                Thread.Sleep(200);

            }

        }

    }

    private static void Thread2() {

        lock(_b) {

            Thread.Sleep(200);

            lock(_a) {

                Thread.Sleep(200);

            }

        }

    }

}