#include <type_traits>

template <typename... Ts>
struct Pack
{
    static constexpr std::size_t size = sizeof...(Ts);
};

template <typename T, typename... Ts>
struct Unique;

template <typename T>
struct Unique<T>
{
    static constexpr int value = 1;
};

template <typename T, typename... Rest>
struct Unique<T, T, Rest...>
{
    static constexpr int value = 0;
};

template <typename T, typename First, typename... Rest>
struct Unique<T, First, Rest...>
{
    static constexpr int value = Unique<T, Rest...>::value;
};


template <typename... Ts>
struct Count_Unique;

template <>
struct Count_Unique<>
{
public:
  static constexpr int value = 0;
};

template <typename Last>
struct Count_Unique<Last>
{
public:
  static constexpr int value = 1;
};

template <typename First, typename... Rest>
struct Count_Unique<First, Rest...>
{
public:
  static constexpr int value = Unique<First, Rest...>::value + Count_Unique<Rest...>::value;
};


int main()
{
    static_assert( Count_Unique<>::value == 0 );
    static_assert( Count_Unique<int, int, int>::value == 1 );
    static_assert( Count_Unique<int, float, int, bool>::value == 3 );
    static_assert( Count_Unique<int, int, int, float>::value == 2 );
    static_assert( Count_Unique<float, int, int, int>::value == 2 );
}