Compilare: user.c: In function ‘check’: user.c:15: warning: unused variable ‘j’ user.c: In function ‘read_and_solve’: user.c:32: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:35: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘main’: user.c:53: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:54: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:58: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result