Compilare: user.c: In function ‘main’: user.c:28: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:29: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:31: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:37: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result