Compilare: user.cpp: In function ‘int main()’: user.cpp:70:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<v[1].size();i++) ^ user.cpp:80:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<v[u].size();i++) ^