Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:40:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[node].size();i++) ^ user.cpp: In function ‘void DFS2(int)’: user.cpp:91:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[node].size();i++) ^ user.cpp: In function ‘void Solve()’: user.cpp:139:13: warning: unused variable ‘ans’ [-Wunused-variable] int ans=0; ^ user.cpp: In function ‘int main()’: user.cpp:155:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker2.out","w",stdout); ^