Compilare: user.cpp: In function ‘int main()’: user.cpp:171:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < adj[node].size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ user.cpp:184:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < rev[node].size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ user.cpp:300:13: warning: unused variable ‘placeholder’ [-Wunused-variable] int placeholder; ^~~~~~~~~~~