class Node {
  public String data;
  public Node link;
}
class Stack {
  public Node top;
}
public class Controller {
  public static void add(Stack s, String data) {
    Node n = new Node();
    n.data = data;
    n.link = s.top;
    s.top = n;
  }
  public static boolean hasMore(Stack s) {
    return s.top != null;
  }
  public static String remove(Stack s) {
    Node n = s.top;
    s.top = n.link;
    return n.data;
  }
}
public class Main {
  public static void main(String args[]) {
    Stack s = new Stack();
    Controller.add(s, "AA");
    Controller.add(s, "BB");
    Controller.add(s, "CC");
    while (Controller.hasMore(s)) {
      String out = Controller.remove(s);
      System.out.println(out);
    }
  }
}