import java.applet.Applet;
import java.awt.*;

public class TwoCounters extends Applet {

    public void init() {
        TextArea display = new TextArea(2, 50);
        add(display);
        SharedNumber count = new SharedNumber(display);

        Counter1 counter1 = new Counter1(count);
        Counter2 counter2 = new Counter2(count);
        counter1.start();
        counter2.start();
    }
} 

class Counter1 extends Thread {
    private SharedNumber count;

    public Counter1(SharedNumber count) {
        this.count = count;
    }

    public void run() {
        for (int i = 1; i <= 10; i++)
            count.increment();
    }
}

class Counter2 extends Thread {
    private SharedNumber count;

    public Counter2(SharedNumber count) {
        this.count = count;
    }

    public void run() {
        for (int i = 1; i <= 10; i++)
            count.increment();
    }
}

class SharedNumber {

    private int n = 0;

    private TextArea display;

    public SharedNumber (TextArea display) {
        this.display = display;
    }

    public void increment() {
        n = n + 1;
        display.append(n + ", ");
    }
}