Compilare: user.c: In function ‘main’: user.c:6: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:7: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:13: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:21: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result