175
Binary
(i.imgur.com)
Post funny things about programming here! (Or just rant about your favourite programming language.)
There are 10 kinds of people in the world. Those who understand binary, those who don't, and those who didn't realise this joke is in base 3.
Actually, there's 2 more:
IIRC the two hardest problems in computer science are cache invalidation, naming things, and off by one errors.
Pretty sure that's the one