interface Animal { 
    void sound(); 
}
abstract class Bird { 
    abstract void fly(); 
}
class Dog implements Animal { 
    public void sound() { 
        System.out.println("Bark"); 
    } 
}
class Sparrow extends Bird { 
    void fly() { 
        System.out.println("Flying"); 
    } 
}
class Test {
    public static void main(String[] args) {
        new Dog().sound();
        new Sparrow().fly();
    }
}