How to link a domain with reg.ru to the heroku app?

Question

Domain Name System

I registered a domain name in reg.ru, added it to heroku (with and without www). Got two *.herokudns.com addresses.
How can I now associate these addresses with the purchased domain in reg.ru? Added CNAME record www -> <some address>.herokudns.com.
I go to www.<my address>, displays Bad Request.
Without www reg.ru, it does not allow creating a CNAME record at all.

Answer 1

https://devcenter.heroku.com/articles/custom-domains
It's simple