Compilare: user.c: In function ‘read’: user.c:208: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:211: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:218: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:221: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘solve’: user.c:233: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result