Problem:
Score : 300 points

Problem Statement

You are given three integers A, B and C. Find the minimum number of operations required to make A, B and C all equal by repeatedly performing the following two kinds of operations in any order:

Choose two among A, B and C, then increase both by 1.

Choose one among A, B and C, then increase it by 2.

It can be proved that we can always make A, B and C all equal by repeatedly performing these operations.

Constraints

0 \leq A,B,C \leq 50

All values in input are integers.

Input

Input is given from Standard Input in the following format:

A B C

Output

Print the minimum number of operations required to make A, B and C all equal.

Sample Input 1

2 5 4

Sample Output 1

2

We can make A, B and C all equal by the following operations:

Increase A and C by 1. Now, A, B, C are 3, 5, 5, respectively.

Increase A by 2. Now, A, B, C are 5, 5, 5, respectively.

Sample Input 2

2 6 3

Sample Output 2

5

Sample Input 3

31 41 5

Sample Output 3

23

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

#!/usr/bin/env stack
-- stack --resolver lts-11.2 script

import Control.Monad ( when )
import Debug.Trace

main :: IO ()
main = do
  ns <- (map read. words) <$> getLine :: IO [Int]

  let ks = filter (\n -> n `mod` 2 /= 0) ns
      gs = filter (\n -> n `mod` 2 == 0) ns

  case length ks of
    0 -> do
      let max   = maximum gs
          toMax = map (\n -> (max-n) `div` 2) gs
      print (sum toMax)
    1 -> do
      let gs'   = map (+1) gs
          max   = maximum $ ks ++ gs'
          toMax = map (\n -> (max-n) `div` 2) $ ks ++ gs'
      print (sum toMax + 1)
    2 -> do
      let ks'   = map (+1) ks
          max   = maximum $ ks' ++ gs
          toMax = map (\n -> (max-n) `div` 2) $ ks' ++ gs
      print (sum toMax + 1)
    3 -> do
      let max   = maximum ks
          toMax = map (\n -> (max-n) `div` 2) ks
      print (sum toMax)