Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:28:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < A[u].size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:41:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("stramosi.in", "r", stdin); ^ user.cpp:42:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("stramosi.out", "w",stdout); ^ user.cpp:44:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d\n", &n, &m); ^ user.cpp:47:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d ", &parent[i]); ^ user.cpp:53:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d\n", &node[i], &question[i]); ^