Calc

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class app extends Applet implements KeyListener {
    int first, second;
    boolean readed;

    public void init() {
        first = second = 0;
        readed = false;
        addKeyListener(this);
    }

    public void keyPressed (KeyEvent me) {
        int u = me.getKeyCode();
        if (u == KeyEvent.VK_ENTER) {
            if (!readed) readed = true;
            else repaint();
        } else {
            int x = me.getKeyChar() - '0';
            if (!readed) first = first * 10 + x;
            else second = second * 10 + x;
            showStatus("" + (readed?second:first));
        }
    }

    public void keyReleased (KeyEvent me) {}

    public void keyTyped (KeyEvent me) {}

    public void paint(Graphics g) {
        if (readed) {
            g.drawString("" + (first + second), 0, 10);
            readed = false;
            first = second = 0;
        }
    }
}