- Time limit: 1.00 s
- Memory limit: 512 MB
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 backwards).
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 \le n \le 10^6
Example
Input:
AAAACACBA
Output:
AACABACAA