class List
{
public:

    List()
        : first {nullptr}
    {}

    void insert(int v)
    {
        first = new Node{v, first};
    }

    int front() const
    {
        return first->value;
    }

    List(List const& other)
        : first {copy(other.first)}
    {}

    ~List()
    {
        while(first != nullptr)
        {
            Node* tmp {first};
            first = first->next;
            delete tmp;
        }
    }

private:

    struct Node
    {
        int value;
        Node* next;
    };

    Node* first;

    Node* copy(Node* p) const
    {
        if (p == nullptr)
        {
            return nullptr;
        }
        return new Node{p->value, copy(p->next)};
    }

};