main = do
    s <- getLine
    putStrLn $ mani s ""
    
mani :: String -> String -> String
mani str res
    | str == []				= res
    | head str == '0'		= mani ( tail str) (res ++ "0")
    | head str == '1'		= mani ( tail str) ( res ++ "1")
    | otherwise				= mani ( tail str) (init res)