Added English version of the site how to do that bots would understand me correctly?

Is there a site that until recently was only Russian version. Now there are English navigation: example.com — Russian en.example.com English.

In each page there

<link rel="alternate" hreflang="en" href="English version">
<link rel="alternate" hreflang="ru" href="Russian version">

robots.txt for both sub-domains must be your own?
sitemap — as the same for all sub-domains are now, with links to the desired language?

Duplication of content will not be? What else do you need to get the full profit?
October 3rd 19 at 03:19
2 answers
October 3rd 19 at 03:21
I usually add both sites in webmaster Google and Yandex and shared regions. More than enough to understand what was happening.
October 3rd 19 at 03:23
Markup as indicated, a subdomain is also true.
Read more here help.yandex.ru/webmaster/yandex-indexing/locale-pages.xml
Each version of the site — a separate site in the eyes of the search engine, so to each his own robots.txt and sitemap.
And both sites separately in the panel Yandex and Google webmaster indicating the region.
Duplication will not, if the sites are really different languages, and not copied a single site.

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