#include <iostream>
#include <memory>
#include <limits>

template <typename T>
struct Node
{
    T value;
    std::unique_ptr<Node<T>> next;
};

template <typename T>
T max(const std::unique_ptr<Node<T>>& node, T max_value)
{
    return (node)
         ?  max(node->next, (node->value > max_value)
                          ?  node->value
                          :  max_value)
         :  max_value;
}

int main()
{
    {
        using NodeT = Node<std::string>;

        auto head = std::make_unique<NodeT>(NodeT{"5", nullptr});
        head->next = std::make_unique<NodeT>(NodeT{"12", nullptr});
        head->next->next = std::make_unique<NodeT>(NodeT{"35", nullptr});
        head->next->next->next = std::make_unique<NodeT>(NodeT{"JKFHDJKSFHKJSDJFSDKH", nullptr});

        std::cout << "Size 1: " << max(head, std::string{}) << '\n';
    }

    {
        using NodeT = Node<int>;

        auto head = std::make_unique<NodeT>(NodeT{1, nullptr});
        head->next = std::make_unique<NodeT>(NodeT{34, nullptr});
        head->next->next = std::make_unique<NodeT>(NodeT{12, nullptr});
        head->next->next->next = std::make_unique<NodeT>(NodeT{-4534, nullptr});
        head->next->next->next->next = std::make_unique<NodeT>(NodeT{std::numeric_limits<int>::max(), nullptr});

        std::cout << "Size 2: " << max(head, std::numeric_limits<int>::min()) << '\n';
    }

    {
        using NodeT = Node<char>;

        auto head = std::make_unique<NodeT>(NodeT{'#', nullptr});

        std::cout << "Size 3: " << max(head, std::numeric_limits<char>::min()) << '\n';
    }

    {
        std::cout << "Size empty: " << max(std::unique_ptr<Node<double>>(), std::numeric_limits<double>::min()) << '\n';
    }
}