template <class T>
class list
{
public:
    class node;
    friend class node;

private:
    node *first, *last;
    size_t node_count;

public:
    class node
    {
        friend class list;

    private:
        const list *owner;
        node *Previous, *Next;

        node(const list *owner)
            : Previous(0), Next(0);

    public:
        T Value;

        ~node();

        node * previous();
        node * next();
    };

    list()
        : node_count(0);

    list(const list &source)
        : node_count(0);

    ~list();

    node * first_node() const;
    node * last_node() const;

    size_t count() const;

    node * add_first(T value);
    node * add_last(T value);
    node * insert_before(node *n, T value);
    node * insert_after(node *n, T value);
};