void addHelper(int data)
    {
        Node *new_node = new Node(data);
        Node *last = head;
        if (head == NULL)
        {
            head = new_node;
            return;
        }
        if (head->getNext() == NULL)
            head->setNext(new_node);
        while (last->getNext() != NULL)
            last = last->getNext();
        return;
    }