interface A {
  void extendInter1();
  void extendInter2();
}
// B now includes extendInter1() and extendInter2() -- it adds extendInter3(). 
interface B extends A {
  void extendInter3();
}
// This class must implement all of A and B
class MyClass implements B {
  public void extendInter1() {
    System.out.println("Implement extendInter1().");
  }
  public void extendInter2() {
    System.out.println("Implement extendInter2().");
  }
  public void extendInter3() {
    System.out.println("Implement extendInter3().");
  }
}
class ExtendInter {
  public static void main(String arg[]) {
    MyClass ob = new MyClass();
    ob.extendInter1();
    ob.extendInter2();
    ob.extendInter3();
  }
}