class Collision {
  //This class represents a collision between two Balls
  public Weight Weight1, Weight2;

  Collision (Weight s1, Weight s2) {
      Weight1 = s1; Weight2 = s2;
  }

  public boolean includes(Weight s) {
      return ((s == Weight1) || (s == Weight2));
  }
  public boolean equals(Collision c) {
     return (c.includes(Weight1) && c.includes(Weight2) ); 
  }
}