// One interface can extend another.
interface A {
  void meth1();
  void meth2();
}

// B now includes meth1() and meth2() - it adds meth2().
interface B extends A {
  void meth3();
}

// This class must implement all of A and B
class MyClass implements B {
  public void meth1() {
    System.out.println("Implement meth1().");
  }
  
  public void meth2() {
    System.out.println("Implement meth2().");
  }
  
  public void meth3() {
    System.out.println("Implement meth3().");
  }
}

class IFExtend {
  public static void main(String args[]) {
    MyClass ob = new MyClass();
    
    ob.meth1();
    ob.meth2();
    ob.meth3();
  }
}