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

class ReactionPanel extends JPanel {
  int size;
  Color color;

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(color); /* initial color wont matter */
    int centerY = super.getHeight()/2;
    int centerX = super.getWidth()/2;
    g.fillOval(centerX, centerY, size, size); /* initial size 0, so initiallly nothin display until you call        setSmallCircle or setBigCircle */
  }

  public void setSmallCircle(Color c) {
    this.color = c;
    size = 10;
    repaint();
  }

  public void setBigCircle(Color c) {
    this.color = c;
    size = 50;
    repaint();
  }
}