import qualified Data.Map.Strict as M

type Count = Int
type Counter a = M.Map a Count

addElement :: Ord a => a -> Counter a -> Counter a
addElement x = M.insertWith (+) x 1

buildCounter :: Ord a => [a] -> Counter a
buildCounter = foldr addElement M.empty

countElem :: Ord a => Counter a -> a -> Count
countElem ctr el = M.findWithDefault 0 el ctr

isKokushi :: Counter Char -> Bool
isKokushi ctr = f 1 == 12 && f 2 == 1 && M.keys ctr == ['a' .. 'm']
    where
        mctr = buildCounter $ M.elems ctr
        f = countElem mctr

solve :: String -> [String]
solve s = (: []) <$> filter g ['a' .. 'z']
    where
        g c = isKokushi $ addElement c ctr
        ctr = buildCounter s

main :: IO ()
main = do
    s <- getLine
    let res = solve s
    if null res then putStrLn "Impossible" else putStr $ unlines res