CTF

<?php
// UwU
include "flag.php";
class Account{
    var $input;
    var $secret;
}
if(isset($_GET['input'])){
    $obj = unserialize($_GET['input']);

    if($obj) {
        $obj->secret = rand(500000,999999);
        if($obj->input === $obj->secret) {
            echo FLAG;
        }
    }
}
show_source(__FILE__);
?>