Compilare: user.cpp: In function ‘void bf(int)’: user.cpp:29:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<vec[x].size();j++) ^ user.cpp: In function ‘int main()’: user.cpp:53:16: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (a!=b) ^