Compilare: user.cpp: In function ‘void bf(int, int)’: user.cpp:12:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[k].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:50:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<popular[i].size();j++) ^