Compilare: user.cpp: In function ‘int main()’: user.cpp:26:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[nd].size();i++) ^ user.cpp:43:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<v[nd].size();i++) ^ user.cpp:9:33: 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:10:35: 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:11:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&n,&m,&nd1,&nd2); ^ user.cpp:14:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^