Compilare: user.cpp: In function ‘int main()’: user.cpp:13:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rege.in","r",stdin); ^ user.cpp:14:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rege.out","w",stdout); ^ user.cpp:16:66: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d%d",&N,&M,&s.first,&s.second,&f.first,&f.second); ^