What you are asking is... is one month from January 30th February (28|29) or is it March (1|2). That's more of a stylistic question, and I guess maybe an option for the user to check. Personally I think I am more of the mind that this is almost a nonsensical question because no logic, math or anything else can really dictate what the correct answer is. The best you can do is just give it a good guess! :)