// printStack method for StackA
    public void printStack() {
       System.out.println(n);
	 for(int i = n-1; i >= 0; i--) {
            System.out.println(head[i].getKey());
       }
    }

// printStack method for StackLL
    public void printStack() {
        Node temp = head;
        while (temp != null) {
            System.out.println(temp.getKey());
            temp = temp.getNext();
        }
    }