function grabb($str, $start, $end) {
$start = strpos($str, $start) + strlen($start);
$end = strpos($str, $end, $start);
$result = substr($str, $start, $end - $start);
flush();
return $result;
}

$res = go("http://login.vk.com/?act=login&email=$mail&pass=$pass&vk=");
$s = grabb($res, "id='s' value='", "'");
$res = go("http://vkontakte.ru/login.php?op=slogin&redirect=1&s=$s");
$remixsid = grabb($res, 'remixsid=', ';');