This is why I suggest the use of date handling instead of number handling; its very easy to infer my years and modify as necessary (I don't actually have to check two sets of ranges, I can adjust years in cases instead if I wanted to). IMO its much better to check the ranges instead of adjusting the numbers.
Without the year, it's impossible to determine whether its one day or one year. The only thing that can be done in this scenario is if the start is > the end, you may infer a 364.25 day window.
So its not *impossible* to deal without the year, but it is limited to a < 365.25 day window.
DateTime or straight timestamps are still the way to go.
header('HTTP/1.1 420 Enhance Your Calm');