Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:21:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v[n].v.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:57:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < res.size(); i++) ^ user.cpp:59:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < res[i].size(); j++) ^ user.cpp:42:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ user.cpp:43:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^ user.cpp:45:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:48:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^