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 = sameIntegersDo

sameIntegers abcs
    | bRem == 0 && aRem == 0    = bN + aN
    | bRem == 1 && aRem == 1    = bN + aN + 1
    | otherwise                 = bN + aN + 2
    where
        [a,b,c] = sort abcs
        (bN, bRem) = (c - b) `divMod` 2
        (aN, aRem) = (c - a) `divMod` 2

sameIntegersDo = do
    abcs <- map read . words <$> getLine
    print $ sameIntegers abcs