import java.util.concurrent.locks.*;

class Monitor {
    Lock lc = new ReentrantLock();
    int sum = 10; 

    public static void main(String[] args) {
        Monitor im = new Monitor();
        Thread t1 = new Thread(new Worker(im));
        Thread t2 = new Thread(new Worker(im));  
        t1.start();
        t2.start();   
    }

    void oek() {
        lc.lock();
        try {
            sum++;
        } finally {
            lc.unlock();
        }
    }
}


class Worker implements Runnable {
    Monitor im;
    
    Worker(Monitor im) {
        this.im = im; 
    }

    @Override 
    public void run() {
        im.oek();
    }
}

class Worker2 extends Thread {
    @Override 
    public void run() {
        System.out.println("Worker 2");
    }
}