Regex – match behind an optional character

I want to match a string that has more than 3 characters and combine with positive look behind an optional character (/).
From the input:

100/ABC-12345 10
ABCD
ZZZ

I need to retrieve:

ABC-12345 10
ABCD

I can match them separately but cannot combine them. See my current regex:

(?<=\/).*

>Solution :

You may use:

(?<=/|^)\w[\w-]{3,}

Updated Regex Demo

Positive lookbehind (?<=/|^) asserts presence of / or start of line behind current position and \w[\w-]{3,} matches at least 4 of word or hyphen characters where first character must be a word character.