Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:23:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < gr[x].size(); i++) { ^ user.cpp: In function ‘int main()’: user.cpp:36:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.in","r",stdin); ^ user.cpp:37:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bfs.out","w",stdout); ^ user.cpp:39:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &n, &m, &s); ^ 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); ^