You are given two $0$ indexed integer arrays fronts and backs, each of length n, representing the numbers written on the front and back of n cards.

You can flip any number of cards. Flipping a card swaps the number on its front with the number on its back.

A number is considered good if it is on the back of at least one card and does not appear on the front of any card.

Return the minimum possible good number. If no good number can be obtained, return $0$.

Constraints:

• n == fronts.length == backs.length

• $1 \leq$ n $\leq 1000$

• $1 \leq$ fronts[i], backs[i] $\leq 2000$

Now, let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Implement your solution in the following coding playground.