import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;

class Punkt {
    private int x, y;

    public Punkt (int x0, int y0) {
	x = x0;
	y = y0;
    }

    public void draw(Graphics g) {
	g.setColor(Color.BLACK);
	g.fillOval(x, y, 10, 10);
    }
}

class Ritpanel extends JPanel implements MouseListener {
    
    public Ritpanel () {
        setBackground( Color.YELLOW );
        addMouseListener(this);
    }

    public void addPunkt (Punkt p) {

	Graphics g = getGraphics();
	p.draw(g);
    }

    public void paintComponent (Graphics g) {
	super.paintComponent(g);

    }
    
    public void mouseClicked (MouseEvent e) {
	Punkt p = new Punkt(e.getX(), e.getY());
	addPunkt(p);
    }

    public void mouseEntered (MouseEvent e) { }
    public void mouseExited (MouseEvent e) { }

    public void mousePressed (MouseEvent e) { }
    public void mouseReleased (MouseEvent e) { }
}
	
class Punkter_1 extends JFrame {

    public Punkter_1 () {

	JPanel s = new Ritpanel();

	add(s);
	setVisible(true);
	setBounds(100, 100, 400, 400);

	setVisible(true);
	setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    public static void main (String[] arg) {

	JFrame f = new Punkter_1();
    }
}