Compilare: user.cpp: In function ‘int main()’: user.cpp:6:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "cal.in" , "r" , stdin ) ; ^ user.cpp:7:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ( "cal.out" , "w" , stdout ) ; ^ user.cpp:8:60: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%ld %ld %ld %ld " , & sx , & sy , & s , & n ) ; ^ user.cpp:11:42: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ( "%ld %ld " , & x , & y ) ; ^