Organizing 1,2,3,4,6,7,8 etc to 1-4, 6-8

Hey Guys,

I have a list of dates that are organized in comma notation, i.e.:

November: 1,2,3,4,5,8,9,11,12,13

Is there any possible way to convert this to:

November: 1-5,8-9,11-13


Any help is appreciated