Compilare: user.cpp: In function ‘void bfs(int, int*)’: user.cpp:24:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<v[i].size();j++) { ^ user.cpp: In function ‘int main()’: user.cpp:57:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<u.size();i++) ^ user.cpp:36:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.in","r",stdin); ^ user.cpp:37:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("graf.out","w",stdout); ^ user.cpp:38:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d",&n,&m,&x,&y); ^ user.cpp:40:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&i,&j); ^