PrintRange

template <typename It>
void PrintRange (It begin, It end){
    bool flag = true;
    for (auto it = begin; it != end; ++ it) {
        if (flag){
            std::cout << *it;
            flag = false;
        } else {
            std::cout << ", " << *it;
        }
    }
    std::cout << std::endl;
}