import Data.List

main = do
  s <- getLine
  maybe (putStrLn "Impossible") (mapM_ putStrLn) (kokushi s)

kokushi s = case sort (map length (group (sort s))) of
  [1,1,1,1,1,1,1,1,1,1,1,1,1] -> Just $ map return "abcdefghijklm"
  [1,1,1,1,1,1,1,1,1,1,1,2] -> let s' = "abcdefghijklm" \\ s in if length s' == 1 then Just [s'] else Nothing 
  _ -> Nothing