You are given a string s consisting of lowercase English letters.

In one operation, you can choose any proper substring of s (a contiguous substring of length strictly less than the length of s) and sort its characters in ascending order.

Return the minimum number of operations needed to sort the entire string s in ascending order. If it is impossible to sort the string, return $-1$.

Constraints:

• $1 \leq$ s.length $\leq 10^5$

• s consists of only 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.