$length = 1;
    for($i = 0; $i < count($list); $i++) {
        foreach($list[$i]['prices'] as $key => $value) {
            sort($list[$i]['prices'][$key]);
            if(count($list[$i]['prices'][$key]) > $length) {
                array_splice($list[$i]['prices'][$key], $length);
            }
        }
    }