7492: [CSES Problem Set] Palindrome Reorder
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Description
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
$1 \leq n \leq 10^6$
Sample 1 Input
AAAACACBA
Sample 1 Output
AACABACAA
Sample 2 Input
ABC
Sample 2 Output
NO SOLUTION