static void shared() {
		int oldVal;
		lock.lock();
		try {
			oldVal = x;
			x ++;
		} finally {
			lock.unlock();
		}
		
		System.out.println(Thread.currentThread().getName() + ":" + oldVal);
		try {
			Thread.sleep(500);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		
//		if (lock.tryLock()) {
//			System.out.println("got lock!");
//		}
	}