What are the three types of problems?
Who is the source of the quote?
I wish I could remember, if I ever knew. I saw the quote years ago,
did not write it down at the time, and AFAIR the three types of
problems weren't specified in the quote. I'm sure it was a comment
made for effect, rather than some authoritative claim. But I think
the point is clear, even if the quote is, in the end, apocryphal.