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 OCaml (4.02.3) (judge verdict: Accepted)

(* O(1) *)
let a, b, c = Scanf.scanf " %d %d %d" @@ fun a b c -> a, b, c
let m = max a @@ max b c
let ec = List.filter (fun n -> n mod 2 = 0) [a; b; c] |> List.length
let x = m + if (ec = 1 || ec = 2) && m mod 2 = 2 - ec then 1 else 0
let _ = Printf.printf "%d\n" @@ (3 * x - (a + b + c)) / 2