int x,y;
int x_direction,y_direction;

void setup(){
  
  y_direction=1;

  size(300,300);

}
void loop(){
  background(255,255,255);

  y=y+y_direction;

  if(y>300-20){
    y_direction=-1;
  }
  if(y<0){
    y_direction=1;
  }

  //1------------------------------------------------
  ellipse(x+13,y,25,25);

 
  //2-----------------------------------

  ellipse(x+50,y,10,10);
 
  //3---------------------------------------------------------

  ellipse(x+90,y,20,20);

  //4--------------------------------------------------------
  ellipse(x+150,y,20,20);

  //5--------------------------------------------------------
  ellipse(x+190,y,30,30);

  //6--------------------------------------------------------
  ellipse(x+240,y,20,20);

  //7--------------------------------------------------------
  ellipse(x+270,y,20,20);

}