Compilare: user.cpp: In function ‘int main()’: user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("secv2m.in","r",stdin); ^ user.cpp:14:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("secv2m.out","w",stdout); ^ user.cpp:15:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d",&N,&M,&L); ^ user.cpp:17:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=N;++i) scanf("%d",&a[i]); ^ user.cpp:18:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (i=1;i<=M;++i) scanf("%d",&b[i]); ^