class Node<E> {
    E data;
    Node<E> next;

    public Node(E data, Node<E> next) {
	this.data = data;
	this.next = next;
    }
    
    public Node(E data) {
	this(data, null);
    }

    public String toString() {
	if (next == null) {
	    return data.toString();
	} else {
	    return data.toString() + ", " + next.toString();
	}
    }
}