DIY: Longest Palindromic Substring

Problem statement

Given a string, s, return the longest palindromic substring in s.

Input

The input will contain a string s. The following is an example input:

"bccd"

Output

The output will be a string representing the longest palindrome. The following is an example output:

"cc"

Coding exercise

Implement the longest_palindrome(s) function, where s is the string. The function returns the longest palindromic substring from s.