Compilare: user.cpp: In function ‘int main()’: user.cpp:10:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] (void)freopen("zero.in", "r", stdin); ^ user.cpp:11:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] (void)freopen("zero.out", "w", stdout); ^ user.cpp:15:55: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] (void)scanf("%llu %llu %llu %llu", &l, &b, &p, &q); ^