Compilare: user.cpp: In function ‘int main()’: user.cpp:89:9: warning: unused variable ‘i’ [-Wunused-variable] int i; ^ user.cpp:91:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zero.in","r",stdin); ^ user.cpp:92:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zero.out","w",stdout); ^ user.cpp:93:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d",&l,&b,&p,&q); ^