import Control.Applicative ((<$>))

main :: IO ()
main = do
    nums <- map (read :: String -> Int) . words <$> getLine
    putStrLn . show $ if (nums !! 0) /= (nums !! 1) 
                      then if (nums !! 0) /= (nums !! 2) then (nums !! 0) else (nums !! 1)
                      else nums !! 2