Returning output before delimiters

Hello:
Struggling for a few days with this. Have tried all sorts of variations of formulas and functions with no luck.
On attached sample file, I have jobs listed in specific buildings, floors, and rooms.
From column B, Room #s, I want to pull the first digit of each room number, separated by commas. That will be the floor number. Column D shows my desired result, and column E shows my desired result, less duplicates.
Column C is my attempted formula. With different formulas, I either get all three room number digits, or, I get the first digit before the first comma only, and not anything from before the remaining commas.
In summary, I want to: separate floor numbers from room numbers, then, eliminate floor number duplicates.

As always, any help would be greatly appreciated! Thank you.

Screenshot 2024-04-16 142629.jpg

Another option

Formula:

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Thank you, very helpful! Fluff13!

These worked great! Thank you so much, TMS!!

Glad to help & thanks for the feedback.