You have a string S. Your task is to rearrange some characters of the string (if needed) so that S[i] is not equal to S[L - i - 1] for each 0 <= i < (L - 1) / 2, where L is the length of S. If multiple rearrangements exist, return the one that comes earliest alphabetically. If there is no answer, print 'impossible.'

Input

The input contains the string S.

Output

Print 'impossible' if there is no answer. Otherwise, print a lexicographical first string that satisfies the given requirements.