abstract class RumorMill {
  abstract int countPeople();
}

class EmptyMill extends RumorMill {
  EmptyMill() { }
  int countPeople() { return 0; }
}

class GossipMill extends RumorMill {
  String name;
  RumorMill next1;
  RumorMill next2;
  GossipMill(String name, RumorMill next1, RumorMill next2)
  {
     this.name = name;
     this.next1 = next1;
     this.next2 = next2;
  }
  int countPeople() { return 1 + this.next1.countPeople()
                         + this.next2.countPeople(); }
}