You are given a positive integer num consisting only of digits $6$ and $9$.

Return the maximum number you can get by changing at most one digit, where a $6$ can be changed to a $9$ or a $9$ can be changed to a $6$.

Constraints:

• $1 \leq$ num $\leq 10^4$

• num consists of only digits $6$ and $9$.

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.