actually, that's a good observation - this question depends a lot on knowing one specific solution to a problem. It really is an old "riddle", as was amusingly

actually, that's a good observation - this question depends a lot on knowing one specific solution to a problem. It really is an old "riddle", as was amusingly observed in the line: "Tim retells an old riddle, though he does not know its origins, and has the words wrong." I knew this was going to be a good one when I read that line, had me chuckling within the first few minutes.