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 Common Lisp (SBCL 1.1.14) (judge verdict: Accepted)

(defun solve (a b c)
  (let* ((maxi (max a b c)) 
         (da (floor (/ (- maxi a) 2)))
         (db (floor (/ (- maxi b) 2)))
         (dc (floor (/ (- maxi c) 2))))
    (setq a (+ a (* da 2)))
    (setq b (+ b (* db 2)))
    (setq c (+ c (* dc 2)))
    (+ (case (- (* 3 maxi) a b c)
         (0 0)
         (1 2)
         (2 1))
       da db dc)))

(princ (solve (read) (read) (read)))