/**
 *	 P.308
 *	 Semaphore.java
 *
 * A basic counting semaphore using Java synchronization.
 */

public class Semaphore
{
   private int s;
   public Semaphore(int value) {
      this.s = value;
   }
   public synchronized void P() {
      while (s == 0) {
         try {
            wait();
         }
         catch (InterruptedException e) { }
      }
      s --;
   }
   public synchronized void V() {
      ++s;
      notify();
   }
}