You are given a string s containing only lowercase English letters. Your task is to repeatedly remove exactly two letters when they are adjacent and equal. Repeat this process until no adjacent equal pair remains.

Return the resulting string after all possible removals. The final output is guaranteed to be unique.

Example 1:

Input: s = "dccbddc"
Output: "dbc"
Explanation:
- First, remove "cc" from "dccbddc" since the letters are adjacent and equal, resulting in "dbddc".
- Remove "dd" from "dbddc", leaving "dbc".
- No further removals can be made, so the final result is "dbc".

Example 2:

Input: s = "xyyxz"
Output: "z"
Explanation:
- Remove "yy" from "xyyxz", resulting in "xxz".
- Remove "xx" from "xxz", leaving "z".
- No more adjacent duplicates exist, so the final output is "z".

Example 3:

Input: s = "xxx"
Output: "x"
Explanation: Remove "xx" from "xxx", leaving "x".
Remember, at each step, only two adjacent equal letters can be removed. We cannot remove three letters at once, even if all three are adjacent and equal, like "xxx".

Constraints:

1 ≤ s.length ≤ 10⁵
s consists only of lowercase English letters (a-z).

10. Remove Adjacent Duplicates