Leftmost Longest Palindrome

Given a string s, return the longest contiguous substring of s that is a palindrome. If several palindromic substrings tie for the longest length, return the one that starts earliest in s. This tie-break makes the answer unique.

Characters are case-sensitive: "Aa" is not a palindrome.

Examples

Example 1

Input: s = "babad"
Output: "bab"
Explanation: "bab" and "aba" both have length 3; "bab" starts earlier.

Example 2

Input: s = "cbbd"
Output: "bb"