Power Automate: How to generate autonumber for every batch of new items in a sharepoint list

Question

Here is the process that I wish to give autonumbers which i would like to call ATSUB# and ATT#: ATSUB#0001 and ATT#0001-01.

1. ATSUB Email is received and comes with attachments that ranges from 1 PDF and up.
2. I already setup a Sharepoint list with the column ATSUB# ATT# and Email ID and Attachment ID.
3. In this Sharepoint list, i would like the ATSUB# to increment per ATSUB email but the number of new items in the list depends on how many attachments there are in the ATSUB email.

Let's say these are the ATSUB Emails in Outlook:

1. ATSUB with 1 PDF on 3/1/2022
2. ATSUB with 2 PFDs on 3/2/2022
3. ATSUB with 2 PDFs on 3/2/2022

The resulting Sharepoint list should look like this:

DATE	ATSUB#	ATT#
3/1/2022	ATSUB#0001	ATT#0001-01
3/2/2022	ATSUB#0002	ATT#0002-01
3/2/2022	ATSUB#0002	ATT#0002-02
3/2/2022	ATSUB#0003	ATT#0003-01
3/2/2022	ATSUB#0003	ATT#0003-02

Thank you so much!!!