Compilare: user.cpp: In function ‘void DoOperation(int, int, int, int, std::set<std::pair<int, std::pair<int, int> > >&)’: user.cpp:78:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < order_vector.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:163:17: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result [-Wunused-result] system("pause"); ^