import Control.Applicative
import Data.List
import Data.Char (digitToInt)

main :: IO ()
main = solve <$> map digitToInt <$> getLine >>= print

solve :: [Int] -> Int
solve xs = fst . maximum $ f (0, xs)
  where f (pt, ss) | length ss < 3 = [(pt,ss)]
                   | otherwise = let xs = do
                                       let l = length ss
                                       i <- [0..l-3]
                                       j <- [i+1..l-2]
                                       k <- [j+1..l-1]
                                       let (x, y, z, zs) = del (i, j, k) ss
                                       if x > 0 && x /= y && y == z then [(pt+100*x+10*y+z, zs)] else [(pt, zs)]
                                 in xs >>= f

del :: (Int,Int,Int) -> [Int] -> (Int, Int, Int, [Int])
del (i,j,k) xs = let (ys1,(x:zs1)) = splitAt i xs
                     (ys2,(y:zs2)) = splitAt (j-i-1) zs1
                     (ys3,(z:zs3)) = splitAt (k-j-1) zs2
                 in (x, y, z, ys1 ++ ys2 ++ ys3 ++ zs3)