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 2.0.3) (judge verdict: Accepted)

(defun solve(a b c)
    (let ((r (- c a))
	  (s (- c b)))
      (cond
	((and (evenp r) (evenp s)) (truncate (+ r s) 2))
	((and (evenp r) (oddp s)) (+ 2 (truncate (+ r s) 2)))
	((and (oddp r) (evenp s)) (+ 2 (truncate (+ r s) 2)))
	(t (truncate (+ r s) 2)))))
		

(defun main()
    (let ((l (sort (read-from-string (concatenate 'string "(" (read-line) ")")) #'<=)))
      (destructuring-bind (a b c) l
	(princ (solve a b c))
	(fresh-line))))

(main)