Compilare: user.cpp: In function ‘void get_hash(std::string, int&, int&)’: user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:53:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < h[r1].size(); ++i) ^