class Flock {
  ArrayList boids;


  Flock() {
    boids = new ArrayList();
  }

  void run() {
    for (int i=0; i<boids.size(); i++) {
      Boid b = (Boid) boids.get(i);
    
      b.run(boids);
    }
  }

  void addBoid(Boid b) {
    boids.add(b);
  }

}