Compilare: user.cpp: In function ‘void df(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:31:29: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(first[x]<first[y]&&last[y]<last[x]||first[x]>first[y]&&last[y]>last[x]) ^