Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:26:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<A[nod].size();++i) {q.push(A[nod][i]);viz[A[nod][i]]=1;} ^ user.cpp:31:29: 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:45:32: 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:46:34: 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:47:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:50:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^