int x;
int speed;

void setup() {
  size(400,400);
  background(255,0,0); 
  x = 200;
  speed = 2;
}

void draw() {
  fill(0,255,0);
  square(50, 100,290 );
  fill(232,250,140);
  square(60,110,270);
  fill(0,255,0);
  square(70,120,250);
  fill(232,250,140);
  square(80,130,230);
  fill(0,255,0);
  square(90,140,210);
  fill(232,250,140);
  square(100,150,190);
  fill(0,255,0);
  square(110,160,170);
  fill(232,250,140);
  square(120,170,150);
  fill(0,255,0);
  square(130,180,130);
  fill(232,250,140);
  square(140,190,110);
  
  fill(158,164, 250);
  ellipse(x,200, 60,60);
  fill(255,0,0);
  ellipse(x,200, 50,50); 
  fill(158,164, 250);
  ellipse(x,200, 40,40);
  fill(255,0,0);
  ellipse(x,200, 20,20);
  x = x + speed;
  if(x > 300) {
    speed = -speed;
  }
  if(x < 100) {
    speed = -speed;
  }
}