we have web with nice url by Helicon ISAPI Rewrite and now we adding 3 language mutations (/en, /de, /ru) and I need to know how to create rewrite rule (redirect) which will add default lang mutation (/en) to the URL, when it does not exists in incoming URL
www.mydomain.com/de/gallery/ -> nothing happend
but
www.mydomain.com/gallery/ -> I need redirect to www.mydomain.com/en/gallery/
Can you help me, please? THX