Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:28:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<a.size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:35:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("darb.in","r",stdin); ^ user.cpp:36:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("darb.out","w",stdout); ^ user.cpp:37:15: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:39:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&x,&y); ^