Two-Letter Card Game

Description

You are given a deck of cards represented by a string array cards, and each card displays two lowercase letters.

You are also given a letter x. You play a game with the following rules:

- Start with 0 points.

- On each turn, you must find two compatible cards from the deck that both contain the letter x in any position.

- Remove the pair of cards and earn 1 point.

- The game ends when you can no longer find a pair of compatible cards.

Return the maximum number of points you can gain with optimal play.

Two cards are compatible if the strings differ in exactly 1 position.