Compilare: user.c: In function ‘read’: user.c:220: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:223: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:230: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:233: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘solve’: user.c:245: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result