let y = 50;

let speed = 1;

​

function setup() {

  createCanvas(400, 400);

}

​

function draw() {

  background(220);

  noStroke();

​

  let y = 25

​

  while (y < width) {

    ellipse(x, y, 50, 50);

    y = y + 50;

  }

​

​

  x = x + speed;

  y = y + speed;

  if (x > width - 50) {

    speed = -1

  } else if (x == 50) {

    speed = 1;

  }

​

​

}