class Animal {}

class Cat extends Animal {
    void myaw() {
        System.out.println("myaw!");
    }
}

class Dog extends Animal {
    void gav() {
        System.out.println("dog!");
    }
}


public class Main {
    public static void main(String[] args) {
        Cat[] cats = { new Cat(), new Cat() };
        Animal[] animals = cats;
        animals[0] = new Dog();
        for (Cat cat: cats) {
            cat.myaw();
        }
    }
}