redirect MT URLs to WP

I struggle when it comes to regexp problems so I’ll ask here.

I have two MT sites I’m moving to WP. I want to put in some nifty .htaccess mod_rewrite code that will redirect people from the older MT URLs to the new WP ones.

1) One of the sites uses the standard MT 3.15 naming convention of https://www.example.com/yyyy/mm/full_title_in_url.html

2) The other site uses a more unconventional convention of https://www.example.com/archives/mmyyFull_title_in_url.html

I would appreciate it if a regex guru gives me some help with what to put into my .htaccess so these URLs will seamlessly redirect to their new WP homes.

Also, will putting in this into my .htaccess interfere with the other rewrite rules used by WP for its regular permalink redirection?