c# - .Net Regex for mm-dd-yy and others + yyymmdd -

i feel chasing tail.

i trying arrive @ .net regex match on following:

mm-dd-yy
m-dd-yy
mm-d-yy
m-d-yy

and (no dashes)

yyyymmdd

one or 2 digits followed dash, followed 1 or 2 digits, followed dash, follows digits or 8 digits:

(\d{1,2}-\d{1,2}-\d{2})|(\d{8})