Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:22:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < vec[n].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:29:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(IA_PROB".in", "r", stdin); ^ user.cpp:30:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(IA_PROB".out", "w", stdout); ^ user.cpp:33:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:41:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^