Compilare: user.cpp: In function ‘bool is_ok(std::pair<int, int>, std::pair<int, int>)’: user.cpp:22:26: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(y.first < x.first && y.second < x.second || y.second < x.first && y.first < x.second) ^ user.cpp: In function ‘void df(int, int)’: user.cpp:30:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[node].size();++i) ^ user.cpp:29:9: warning: unused variable ‘max_depth’ [-Wunused-variable] int max_depth = level; ^