Compilare: user.cpp: In function ‘void df(int, int)’: user.cpp:55:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[x].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:83:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<ans.size(); ++i) ^ user.cpp:85:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<ans[i].size(); ++j) ^