One From Each Shelf

Store rules: pick exactly one snack from shelf A and one from shelf B, spending exactly the coupon. 🛒

You get shelf a prices, shelf b prices, and the coupon. Print possible if some A-item plus some B-item equals the coupon exactly, otherwise impossible.

Example:

Input: a = [3, 7, 2], b = [5, 4], coupon = 6 Output: possible

2 (from shelf A) plus 4 (from shelf B) equals the coupon exactly.