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)

module Main (main) where

import qualified Data.ByteString.Char8     as C8
import           Data.Maybe

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

type Input  = (Int, Int, Int)
type Output = Int

solve :: Input -> Output
solve (a,b,c)
  | a == b    = c
  | a == c    = b
  | otherwise = a

showAnswer :: Output -> Answer
showAnswer = Number

-- utils
readInts :: IO [Int]
readInts = map (fst . fromJust . C8.readInt) . C8.words <$> C8.getLine

data Answer
  = YesNo Bool
  | AB Bool
  | Number Int

instance Show Answer where
  show (YesNo b)  = if b then "Yes" else "No"
  show (AB b)     = if b then "A"   else "B"
  show (Number i) = show i