I majored in math at the graduate level and I think I am qualified to make such a statement.
You need to apologize to RF for being a jerk.
Let's see if you as good at gentlemanly behavior as you are at math.
BTW, I got the answer to this problem in about an hour of noodling. Look upthread.
What exactly do you think math is? Calculation? How did you get through graduate courses in mathematics without being disabused of that notion?
Evidently in Singapore people still remember what mathematics actually is so that they give little miniature exercises in the construction of proofs on their math exams.
I, too majored in mathematics at a graduate level, clear through a Ph.D., am a working mathematician, and took multiple semesters of *logic* in graduate school — good stuff like intuitionistic logic (including sheaf semantics), lambda calculus, and Martin-Lof type-theory.
That so many people (from among FReepers, a generally well-read and sophisticated bunch) want to claim that the problem had “no math involved”, including people who taught mathematics in the K-12 schools and took graduate courses in math, suggests that the rot in American mathematics education those of us teaching at universities have long been aware of is deeper, older, and more pervasive than we had thought.