Compilare: user.c: In function ‘readdata’: user.c:38: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:39: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:42: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c: In function ‘buildtree’: user.c:140: warning: unused variable ‘p’ user.c: In function ‘compute’: user.c:269: warning: unused variable ‘p’ user.c: In function ‘outputdata’: user.c:333: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c: In function ‘locate’: user.c:176: warning: ‘poz’ may be used uninitialized in this function