Aiogram How to reply to messages with media_group?

Question

Bots

The bot must accept:
- a document (photos and files) from the user;
- assignment to the document.

While the user sends 1 file - there are no problems.

If the user sends multiple photos (album), the bot treats each photo as a separate message, which causes any bot response to be multiplied by the number of photos sent by the user.

I'm trying to do the following:
1. Write the id of all incoming photos to the dictionary - it worked;
2. Reply to the user that his message has been received (1 time, but preferably specifying the number of documents sent). Here, for now, it turns out only to send him X answers indicating this very X photos.