[hardwired]

import java.util.Vector;

public class Test {
    public static void main(String[] args) {
        Vector<Animal> v = new Vector<Animal>();
        for(int i = 0; i < 3; i++) {
            v.add(new Cat(i));
        }
        for(int i = 0; i < v.size(); i++) {
            System.out.println(v.get(i));
        }
    }
}

class Animal {
    public String toString() {
        return getClass().getName();
    }
}

class Cat extends Animal {
   int n;

    public Cat(int n) {
        this.n = n;
    }

    public String toString() {
        return super.toString() + "[n: " + n + "]";
    }
}