class Animal {
  public void makeSound() {
    System.out.println("Some generic animal sound");
  }
}

class Dog extends Animal {
  @Override
  public void makeSound() {
    System.out.println("Woof");
  }
}

class Cat extends Animal {
  @Override
  public void makeSound() {
    System.out.println("Meow");
  }
}

public class Main {
  public static void main(String[] args) {
    Animal a = new Dog();
    a.makeSound(); // prints Woof
    a = new Cat();
    a.makeSound(); // prints Meow
  }
}