<?php
$a[] = '56';
$a[] = '66';
$a[] = '';
$a[] = '58';
$a[] = '85';
$a[] = '';
$a[] = '';
$a[] = '76';
$a[] = '';
$a[] = '57';
echo $average;
PD9waHAKJGFbXSA9ICc1Nic7CiRhW10gPSAnNjYnOwokYVtdID0gJyc7CiRhW10gPSAnNTgnOwokYVtdID0gJzg1JzsKJGFbXSA9ICcnOwokYVtdID0gJyc7CiRhW10gPSAnNzYnOwokYVtdID0gJyc7CiRhW10gPSAnNTcnOwokYSA9IGFycmF5X2ZpbHRlcigkYSk7CiRhdmVyYWdlID0gYXJyYXlfc3VtKCRhKS9jb3VudCgkYSk7CmVjaG8gJGF2ZXJhZ2U7