void setup() {
  size(600, 600);
}
void draw() {
  background(0);
  //rectangles on the left side
  for (int i = 0; i < 7; i++){
     rect(50, 50 + i * 75, 50, 50);
  }
  //rectangles on the right side
  for (int i = 0; i < 7; i++){
     rect(500, 50 + i * 75, 50, 50);
  }
  //circles in the middle
  for(int i = 0; i < 5; i++){
     ellipse(200 + 40*i,200,40,40);
  }
  //triangles in the middle
  for(int i = 0; i<4; i++){
    triangle(175 + 85*i,50, 200 + 85*i, 100, 150 + 85*i, 100);
  }