Given a string s representing an integer, return the largest even integer as a string that can be formed by deleting zero or more characters from s. If no even number can be formed, return an empty string "".

Constraints:

• $1 \leq$ s.length $\leq 100$

• s consists only of the characters $'1'$ and $'2'$.

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.