Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:29:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<A[x].size();++i) ^ user.cpp: In function ‘int main()’: user.cpp:41:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fof.in","r",stdin); ^ 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("fof.out","w",stdout); ^ user.cpp:43:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:46:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^