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 Control.Applicative
import Data.List

main = do
    nums@[a,b,c] <- sort.map read.words <$> getLine :: IO [Int]
    if c == a && c == b then putStrLn "0" else putStrLn.show $ count 0 [a,b,c]

count n [a,b,x] = if a' == x && b' == x then (n+1) else count (n+1) nums where
    nums = sort [x,a',b']
    x' = foldl max 0 [x,a',b']
    (a',b') = if (x >= a+2) then (a+2,b) else  (a+1,b+1)