public class UseStack {
    public static void main(String[ ] args) {
        System.out.println("Hello World!");
        Stack s = new Stack();
        Integer i = new Integer(27);  s.push(i);
        Integer j = new Integer(42);  s.push(j);
        Integer k = new Integer(69);  s.push(k);
        System.out.println(s.pop().toString());
        System.out.println(s.pop().toString());
        System.out.println(s.pop().toString());
        System.out.println(s.pop().toString());
    }
}