Can Form Palindrome

Given a string s consisting of lowercase letters, determine whether it is possible to rearrange the characters of s to form a palindrome. A palindrome is a string that reads the same backwards as forwards. Mathematically, a string can be rearranged into a palindrome if and only if the number of characters with an odd frequency is at most one, i.e., $$ \#\{c : freq(c) \text{ is odd}\} \le 1.$$

If a palindromic arrangement exists, output one possible arrangement; otherwise, output an empty string.

inputFormat

The input consists of a single line containing the string s (possibly empty) made up of lowercase English letters.

outputFormat

Output a single line containing one possible palindromic arrangement of s if one exists. If it is impossible to form any palindrome, output an empty string.

code