import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.concurrent.locks.Condition;

class Monitor {
    private int number = 0;
    private Lock lock = new ReentrantLock();
    private Condition over9000 = lock.newCondition();

    public void increment() {
        lock.lock();
        try {
            number++;

            if (number > 9000) {
                over9000.signal();
            }
        } finally {
            lock.unlock();
        }
    }

    public int hentTall() {
        lock.lock();
        try {
            return number;
        } finally {
            lock.unlock();
        }
    }

    public void reduce() {
        lock.lock();
        try {
            while (number <= 9000) {
                over9000.await();
            }

            number -= 3000;
        } catch (InterruptedException ie) {
            System.out.println("Interrupted");
        } finally {
            lock.unlock();
        }
    }
}