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

solve :: (Int, Int, Int) -> Int
solve (a,b,c) 
    | c - b == 1 = 1 + solve (a+1,c,c)
    | c - b > 0 && even (c-b) = (c-b) `quot` 2 + solve (a,c,c) 
    | c - b >= 3 = 1 + solve (a+1,b+1,c)
    | c == b && even (b-a) = (b-a) `quot` 2
    | c == b && odd (b-a) = 1 + solve (a,b+1,c+1)

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