Compilare: user.cpp: In function ‘int main()’: user.cpp:19:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pal.in", "r", stdin); ^ user.cpp:20:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("pal.out", "w", stdout); ^ user.cpp:21:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &l); v1=-1; v2=-1; for (i=1; i<=S; ++i) a[i]=b[i]=-1; ^ user.cpp:24:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &ap[i]); S+=ap[i]; ^