class D extends C {
  void x() {
    System.out.println(1);
  }

}
class C extends B {
  void x() {
    System.out.println(2);
  }

}
class B {
  void x() {
    System.out.println(3);
  }
  void y(B b) {
    b.x();

  }
  void y(C c) {
    c.x();

  }
  void y(D d) {
    d.x();

  }

}
class A {
  public static void main(String[] args) {
    new B().y(new C());

  }

}