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)

import Data.List

main :: IO ()
main = do
  as <- map read . words <$> getLine
  let [a,b,c] = sort as
  print $ solve a b c

solve :: Int -> Int -> Int -> Int
solve a b c | even (c-a) && even (c-b) = (c-a) `div` 2 + (c-b) `div` 2
            | even (c-a) || even (c-b) = (c-a) `div` 2 + (c-b) `div` 2 + 2
            | otherwise = (c-a-1) `div` 2 + (c-b-1) `div` 2 + 1