#include <iostream>

template <int n, int x, int... xs>
struct is_unique {
  static const bool value = x != n &&is_unique<n, xs...>::value;
};

template <int n, int x>
struct is_unique<n, x> {
  static const bool value = x != n;
};

template <int n>
struct unique_acc {
  static const int value = n;
};

template <typename acc, int... xs>
struct unique_n {
  static const int value = is_unique<acc::value, xs...>::value ?
   acc::value :
   unique_n<unique_acc<acc::value + 1>, xs...>::value;
};

template <int... xs>
struct unique_n<unique_acc<sizeof...(xs)>, xs...> {
static const int value = sizeof...(xs);
};

template <int... xs>
using unique = unique_n<unique_acc<0>, xs...>;

enum my_enum {
  a = 5,
  b = 2,
  c = 0
};

int main() {
  std::cout << unique<a, b, c>::value;
}