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

public class UpDown extends Applet implements Runnable
{
 int x=20, y=0;
 int ydir=1, pauza=2, raza=20;
 int xdir=1;
 
 public void paint(Graphics g)
 {
  g.fillOval(x,y,2*raza,2*raza);
 }
      public void run()
      {
       while(true)
       {
        if((y+ydir+2*raza>getSize().height) || (y+ydir<0))
            ydir*=-1;
        if((x+xdir+2*raza>getSize().width) || (x+xdir<0))
            xdir*=-1;
            y+=ydir;
            x+=xdir;
        repaint();
        try{Thread.sleep(pauza);}
        catch(Exception e){};
       }
       
      }

      
     public void init()  
     {
         setBackground(Color.red);
         addMouseListener(new MouseAdapter(){
         public void mouseClicked(MouseEvent e)
         {x=e.getX();
          y=e.getY();
         repaint();
         
         }
         
         
         });
      new Thread(this).start();   
     }
     
      
   }