Compilare: user.cpp: In function ‘int main()’: user.cpp:36:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("schi.in","r",stdin); ^ user.cpp:37:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("schi.out","w",stdout); ^ user.cpp:39:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:41:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&a[i]); ^ user.cpp: In function ‘int cb(int)’: user.cpp:31:12: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized] return val; ^