ball b1, b2, b3;

void setup()
{
  size(600,600);
  b1 = new ball(100, 80, 'A');
  b2 = new ball(200, 80, 'B');
  b3 = new ball(300, 80, 'C');
}

void draw()
{
  background(255);
  b1.display();
  b2.display();
  b3.display();
  
  b1.fall(2);
  b2.fall(1);
  b3.fall(3);
 
}

void keyPressed()
{
  if (key == b1.letter)
    b1.moveTop();
    
  if (key == b2.letter)
    b2.moveTop();
  
   if (key == b3.letter)
    b3.moveTop();
  
}