Github: https://github.com/BunnyHeist/CSEC
Given a string, your task is to reorder its letters in such a way that it becomes a palindrome (i.e., it reads the same forwards and backward).
Input
The only input line has a string of length n consisting of characters A–Z.
Output
Print a palindrome consisting of the characters of the original string. You may print any valid solution. If there are no solutions, print "NO SOLUTION".
Constraints
1≤n≤106
Example
Input:
AAAACACBA
Output:
AACABACAA
