Compilare: user.c: In function ‘main’: user.c:26: warning: suggest parentheses around comparison in operand of ‘&’ user.c:16: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:17: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:19: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result