Problem Statement

You are given a string $S$ of length 13 consisting of the 13 kinds of lowercase letters abcdefghijklm, each appearing 0 or more times.
Determine whether, by adding one character to $S$, it can be made to contain exactly two of one of the letters in abcdefghijklm and exactly one of each of the other letters.

Input

$S$

$S$ is given on one line.

Output

If the condition can be satisfied, output the character to add (there may be multiple possibilities. In that case, output them in lexicographical order, separated by newlines.); otherwise, output Impossible on one line.
Print a newline at the end.

Sample

abcdfghijklmm

e

abcdefgmmmmmm

Impossible

cbmlieadfghjk

a
b
c
d
e
f
g
h
i
j
k
l
m