#include <iostream>
#include <thread>
#include <string>
#include <thread>
#include <mutex>

template <typename ...Arg>
concept is_fucking_string = (std::is_convertible_v<Arg, std::string> && ...);

template <typename T,typename...Pack>
concept is_same = requires(T t,Pack...pk)
{
    requires(std::is_same_v<T, Pack> && ...);


};
template <typename T,typename ...Arg>
concept mixin = is_fucking_string<Arg...> && is_same<T,Arg...>;
template <typename T,typename ...Arg>
decltype(auto) foo(T t,Arg...arg) requires mixin<T,Arg...>
{
    return (std::string(t) + ... + std::string(arg));
}
template <typename T,typename ...Arg>
decltype(auto) foo(T t,Arg...arg) requires is_same<T,Arg...>
{
    return (arg + ...);
}
int main()
{
    std::cout << foo("33","gg");

}