#include <iostream>
template <typename ...P> struct sum_type;
template <typename T>
struct sum_type<T>{
using type=T;
};
template <typename T, typename ...P>
struct sum_type<T, P...>{
using type=decltype(T()+typename sum_type<P...>::type());
};
template <typename ...P>
using sum_type_t=typename sum_type<P...>::type;
template <typename T>
inline T sum(T t){ return t; }
template <typename T, typename ...P>
inline sum_type_t<T, P...> sum(T t, P... p){
return t+sum(p...);
}
int main(void){
auto s=sum(-7, 3.7f, 9u, -2.6);
auto s2=sum(-7, 3.7f, 9u -42.6);
std::cout<<"s is "<<s<<" and its type is "<<typeid(s).name()<<'\n';
std::cout<<"s2 is "<<s2<<" and its type is "<<typeid(s2).name()<<'\n';
return 0;
}