Compilare: user.cpp: In function ‘int main()’: user.cpp:19:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<s.length(); i++) ^ user.cpp:26:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<v.size(); i++) ^ user.cpp:28:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0; j<q[v[i]].size(); j++) ^