If we can assume that
first-category don't contain digits, we can simply search for the first non-empty string of numbers and delete everything else.
Find what: (.*?)(\d+).*
Replace with: \2
How it works:
.* is any arbitrary string of characters
.* lazy, i.e., it matches as few characters as possible
\d+ is a non-empty string of digits
() groups characters, where
\2 refers to the second group
For more information about Regular Expressions, click here.
gets replaced with