Given a string s of length n, find the smallest index i such that s[i] is equal to s[n - 1 - i].

Return the minimum valid index i. If no such index exists, return $-1$.

Constraints:

• $1 \leq n ==$ s.length $\leq 100$

• s consists of lowercase English letters.

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.