public class BSem {
    int value;

    // Constructor. If parameter is 0, then semaphore is initally zero
    // Otherwise, it is one.
    public BSem(int initial) {
	if (initial == 0) value = 0;
	else value = 1;
    }

    public synchronized void P( ) {
	while (value == 0) 
	    try {
		wait();
	    }
	    catch (java.lang.InterruptedException e) { };
	value = 0;
    }

    public synchronized void V( ) {
	value = 1;
	notify();
    }
}