Problem:
Score : 100 points

Problem Statement

You are given three integers, A, B and C.

Among them, two are the same, but the remaining one is different from the rest.

For example, when A=5,B=7,C=5, A and C are the same, but B is different.

Find the one that is different from the rest among the given three integers.

Constraints

-100 \leq A,B,C \leq 100

A, B and C are integers.

The input satisfies the condition in the statement.

Input

Input is given from Standard Input in the following format:

A B C

Output

Among A, B and C, print the integer that is different from the rest.

Sample Input 1

5 7 5

Sample Output 1

7

This is the same case as the one in the statement.

Sample Input 2

1 1 7

Sample Output 2

7

In this case, C is the one we seek.

Sample Input 3

-100 100 100

Sample Output 3

-100

Solution in Haskell (GHC 7.10.3) (judge verdict: Accepted)

{-# 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