import java.util.Stack; class Main { public static void main(String[] args) { System.out.println("Hello World!"); Stack<Dog> p = new Stack(); Dog d = new Dog(); Labradoodle l = new Labradoodle(); //Number 2 p.push(l); d = p.pop(); //Number 4 p.push(l); l = (Labradoodle) p.pop(); } }