-- Based on http://stackoverflow.com/questions/30551033/swap-two-elements-in-a-list-by-its-indices
swapElementsAt :: Int -> Int -> [a] -> [a]
swapElementsAt i j xs = left ++ [elemJ] ++ middle ++ [elemI] ++ right
    where
        elemI = (!!) xs $ min i j
        elemJ = (!!) xs $ max i j
        left = take i xs
        middle = take (j - i - 1) $ flip drop xs $ i + 1
        right = flip drop xs $ j + 1

swapDigitsAt :: Int -> Int -> Int -> Int
swapDigitsAt i j = read . swapElementsAt i j . show

getMaximum :: Int -> Int
getMaximum n = maximum [swapDigitsAt i j n | j <- [1 .. l - 1], i <- [0 .. j - 1]]
    where
        l = length $ show n

main :: IO ()
main = print . getMaximum =<< readLn