LocationHelper::getParentId

static function getParentId($id)
{
	if(!($id = intval($id)))
		return 0;

	$class = static::getEntityClass('main');
	$item = $class::getList(array(
		'filter' => array('=ID' => $id),
		'select' => array('PARENT_ID')
	))->fetch();

	return $item['PARENT_ID'];
}