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

func [a,b,c]
 |even a == even b && even b == even c = [a,b,c,0]
 |even a == even b = [a+1,b+1,c  ,1]
 |even a == even c = [a+1,b  ,c+1,1]
 |even b == even c = [a  ,b+1,c+1,1]

main = do
 list <- map read . words <$> getLine
 let [a,b,c,d] = func list
     largest = maximum [a,b,c]
 print $ d+abs (largest-a) `div` 2 + abs (largest-b) `div` 2 + abs (largest-c) `div` 2