Q:

Shorter regex for days of week/months range

I need a regex to match the days of week in two formats: the normal way, like "mon", "fri", etc, but I also need in the same regex for a range type of format, like "mon-fri"
Same for months:
"jan", "feb"
"jan-dec"
I have this working regex:
^((jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)|((jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)-(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)))$
But it's huge and not sure if ideal. 

A:

^(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)(-(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec))?$

