Compilare: user.cpp: In function ‘int main()’: user.cpp:35:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<v[w.front()].size(); i++) ^ user.cpp:50:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<v[w.front()].size(); i++) ^ user.cpp:73:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<s.size(); i++) ^