import javax.swing.JFrame;

import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;

class Ekran extends Canvas {
    private static final int POINT_SIZE = 100;
    private Point point;

    Ekran() {
        super();
        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent me) {
                point = new Point(me.getX(), me.getY());
                repaint();
            }
        });
    }

    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        g2.setColor(Color.RED);
        if (point != null) {
            int x = (int) point.getX();
            int y = (int) point.getY();
            g2.fillOval(x - POINT_SIZE / 2, y - POINT_SIZE / 2, POINT_SIZE, POINT_SIZE);
        }
    }
}