import qualified Data.List as DL

main = do
    s <- getLine
    putStrLn $ showResult $ solve s

solve :: String -> [Char]
solve s = filter (\c -> valid (c:s)) ['a'..'m']
    where valid cs = (length $ DL.nub cs) == 13

showResult :: [Char] -> String
showResult [] = "Impossible"
showResult cs = unlines $ map (\c -> [c]) cs