#ifndef CLASS_TUPLE
#define CLASS_TUPLE

#include <type_traits>

namespace std
{
    template<class T>
        struct tuple_size;

//    template<std::size_t I, class... Types>
//        struct tuple_element;
    
    template<size_t __i, typename _Tp>
        struct tuple_element;
    
};

static constexpr int maximum(int a, int b)
{
    if (a > b)
        return a;
    return b;
}

template<int index, typename A = void, typename... Args>
    struct ArgType
    {
        using type =
            typename std::conditional<
                index == 0,
                A,
                typename ArgType<maximum(index - 1, 0), Args...>::type>::type;
    };

template<typename T>
    struct ArgType<0, T>
    {
        using type = T;
    };

template<typename... Ts>
    class tuple
    {
        public:
            struct empty
            {
                auto operator <=> (const empty& other __attribute__((unused))) const
                {
                    return 0;
                }
            };
            
            template <size_t _index, typename M = void, typename... Es>
                struct elements_t
                {
                    static const size_t index = _index;
                    
                    M car;
                    
                    typename std::conditional<
                        sizeof...(Es) == 0,
                        empty,
                        elements_t<_index + 1, Es...>>::type cdr;
                    
                    elements_t()
                    {
                        ;
                    }
                    
                    elements_t(M m, Es... e):
                        car(m), cdr(e...)
                    {
                        ;
                    }
                    
                    int operator <=> (const elements_t& other) const
                    {
                        auto car_res = (car <=> other.car);
                        
                        if (car_res > 0)
                            return 1;
                        if (car_res < 0)
                            return -1;
                        
                        auto cdr_res = (cdr <=> other.cdr);
                        
                        if (cdr_res > 0)
                            return 1;
                        if (cdr_res < 0)
                            return -1;
                        
                        return 0;
                    }
                };
        
        public:
            elements_t<0, Ts...> elements;
        
        public:
            tuple()
            {
                ;
            }
            
            tuple(Ts... _elements):
                elements(_elements...)
            {
                ;
            }
            
        private:
            template<size_t index, typename R, typename T>
                R& helper(T& holder)
                {
                    if constexpr(T::index == index)
                        return holder.car;
                    else
                        return helper<index, R>(holder.cdr);
                };
        
        public:
            template<size_t index>
                ArgType<index, Ts...>::type& get()
                {
                    return helper<index, typename ArgType<index, Ts...>::type>(elements);
                }
            
            auto first()
            {
                return this->get<0>();
            }
            
            auto second()
            {
                return this->get<1>();
            }
            
            int operator <=> (const tuple& other) const
            {
                return elements <=> other.elements;
            }
            
            ~tuple()
            {
                ;
            }
    };


template<typename... Ts>
    struct std::tuple_size<tuple<Ts ...>>
    {
        static constexpr size_t value = sizeof...(Ts);
    };

template<class car, class... cdr>
    struct std::tuple_element<0, std::tuple<car, cdr ...>>
    {
        using type = car;
    };

template<std::size_t I, class car, class... cdr>
    struct std::tuple_element<I, std::tuple<car, cdr ...>>:
        std::tuple_element<I - 1, std::tuple<cdr ...>>
    {
    };

template<class car, class... cdr>
    struct std::tuple_element<0, tuple<car, cdr ...>>
    {
        using type = car;
    };

template<std::size_t I, class car, class... cdr>
    struct std::tuple_element<I, tuple<car, cdr ...>>:
        std::tuple_element<I - 1, tuple<cdr ...>>
    {
    };























#endif