Compilare: user.cpp: In function ‘int main()’: user.cpp:168:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < adj[node].size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ user.cpp:181:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < rev[node].size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ user.cpp:295:13: warning: unused variable ‘placeholder’ [-Wunused-variable] int placeholder; ^~~~~~~~~~~