Compilare: user.cpp: In function ‘int main()’: user.cpp:51:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.in","r",stdin); ^ user.cpp:52:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.out","w",stdout); ^ user.cpp:53:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&m,&n,&k); ^ user.cpp:54:58: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i=1;i<=k;i++) scanf("%d%d",&ve[i].x,&ve[i].y); ^