Compilare: user.cpp: In function ‘int main()’: user.cpp:11:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("subsir2.in","r",stdin); ^ user.cpp:12:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("subsir2.out","w",stdout); ^ user.cpp:16:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:17:46: 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:43:20: warning: ‘first’ may be used uninitialized in this function [-Wmaybe-uninitialized] while(fiu[first]) ^