The Matching Mittens

Mittens come in matched pairs: -3 pairs with 3, -7 with 7. One matched pair got separated in the pile! 🧤

You get the mitten nums (exactly one value appears together with its exact negative; no zeros). Print the POSITIVE half of the matched pair.

Example:

Input: nums = [4, -7, 9, 7, 2] Output: 7

-7 and 7 sum to exactly zero, and 7 is the positive half of that matched pair.