using System;

using System.Threading;

​

public class LockStatement 

{ 

    static SemaphoreSlim _sem = new SemaphoreSlim (3); // Capacity of 3 

    public static void Main()

    {   

        //Console.Clear();

        for (int i = 1; i <= 5; i++) new Thread (Enter).Start (i); 

    }

    static void Enter (object id)

    {

        var id_ = (int) id;

        Console.WriteLine (id_ + " wants to enter");

​

        _sem.Wait();

        Console.WriteLine (id_ + " is in!"); // Only three threads

        Thread.Sleep(1000 * id_); // can be here at

        Console.WriteLine (id_ + " is leaving"); // a time.

        _sem.Release();

    }

}