Two switches, each represented by an int where 0 means off and any nonzero value means on. Print On if
exactly one of them is on – both off, or both on, both print Off.
This is worth building entirely out of &&, ||, and !, without writing a single if: “exactly one of two
things is true” is “(the first is true and the second isn’t) or (the second is true and the first isn’t)” –
translate that sentence directly into &&/||/!, one piece at a time, rather than trying to guess the whole
expression at once. This also uses the ternary operator from this lesson to pick the string to print, all in one
printf call.