Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:22:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a[bf[0]].size();i++) ^ user.cpp: In function ‘int main()’: user.cpp:40:32: 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:41:34: 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:46:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ", &x, &y); ^