class A {
  public static String f = "a";
}
class B extends A {
  public static String f = "b";
}
class C extends B {
  public static String f = "c";
}
class D extends A {
  public static String f = "d";
}
public class Stat {
  public static void main(String args[]) {
    System.out.println(A.f);
    System.out.println(B.f);
    System.out.println(C.f);
    System.out.println(D.f);
    A a = new A();
    A b = new B();
    A c = new C();
    A d = new D();
    System.out.println(a.f);
    System.out.println(b.f);
    System.out.println(c.f);
    System.out.println(d.f);
  }
}