Compilare: user.cpp: In function ‘void add(int, int)’: user.cpp:20:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < h[key].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:48:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < h[i].size(); ++j) ^