SELECT ?lang (COUNT(DISTINCT ?item) AS ?count) WHERE {
  SERVICE wikibase:mwapi {
    bd:serviceParam wikibase:endpoint "ru.wikipedia.org" .
    bd:serviceParam wikibase:api "Generator" .
    bd:serviceParam mwapi:generator "search" .
    bd:serviceParam mwapi:gsrsearch "deepcat:Объекты_культурного_наследия_России_в_Ростовской_области" .
    bd:serviceParam mwapi:gsrlimit "max" .
    ?item wikibase:apiOutputItem mwapi:item .
  }
  ?sitelink schema:about ?item .
  FILTER (SUBSTR(str(?sitelink), 11, 15) = ".wikipedia.org/") .
  ?sitelink schema:inLanguage ?lang
}
GROUP BY ?lang
ORDER BY DESC (?count)