You are given a string S$,$ which consists entirely of decimal digits $(0-9).$ Using digits from S$,$ create a palindromic number with the largest possible decimal value. You should use at least one digit and you can reorder the digits. A palindromic number remains the same when its digits are reversed; for instance, $"7","44"$ or $"83238".$ Any palindromic number you create should not, however, have any leading zeros, such as in $"0990"$ or $"010".$

For example, decimal palindromic numbers that can be created from $"8199"$ are: $"1","8","9","99","919"$ and $"989".$ Among them, $"989"$ has the largest value.

Write a function:

class Solution public String

solution$($String S$)$:$)$

that, given a string S of N digits, returns the string representing the palindromic number with the largest value.

Examples:

$1.$ Given $"39878",$ your function should return $"898".$