public class Leaf extends Component {
  public Leaf(String name) {
    super(name);
  }

  public void add(Component c) {
    System.out.println("LeafにはComponentを追加できません");
  }
  public void remove(Component c) {
    System.out.println("Leafから削除できるComponentはありません");
  }
  public void display() {
    System.out.println(name);
  }
}