That's one valid approach. The other valid approach would be to OR the admissible cases together:
[EDIT]: See Plato's post below for a correction to this approach.
I think you'll find this approach more scalable, if you throw more guys into the mix!
Incidentally, because disjunction is associative, you probably don't need that many parentheses, unless your teacher is being a stickler about wff's.