Is it possible to move the CMS to a subfolder but keep addressing from the root?

Question

htaccess

I want to put the CMS in the /october/ folder, but make a redirect so that the pages go from the root: example.com/my_page.html I

wrote the rules:

RewriteCond %{REQUEST_URI} !^/october/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /october/$1
RewriteRule ^(/)?$ october/index.php [L]

Everything is fine, but now the content is available both directly /page, and at the real address /october/page. I couldn't handle the duplication. Tried to close access to /october/ but got a server error. Looks like the poor Apache got stuck in a loop... How do I make the redirect right?