{-# OPTIONS_GHC -O2 -funbox-strict-fields #-}
import qualified Data.ByteString.Char8 as BC
import           Data.Maybe            (fromJust)

main :: IO ()
main = do
  [a, b, c] <- getInts
  print $ solve a b c

solve :: Int -> Int -> Int -> Int
solve a b c
  | a == b    = c
  | b == c    = a
  | otherwise = b

readInts :: BC.ByteString -> [Int]
readInts = map (fst . fromJust . BC.readInt) . BC.words

getInts :: IO [Int]
getInts = readInts <$> BC.getLine
