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 Ruby (2.3.3) (judge verdict: Accepted)

a,b,c = gets.split.map(&:to_i).sort.reverse

if a[0] == b[0] && a[0] == c[0]
  puts (a - b) / 2 + (a - c) / 2
elsif b[0] == c[0]
  puts (a - (b + 1)) / 2 + (a - (c + 1)) / 2 + 1
elsif a[0] == b[0]
  puts ((a + 1) - (b + 1)) / 2 + ((a + 1) - c) / 2 + 1
elsif a[0] == c[0]
  puts ((a + 1) - b) / 2 + ((a + 1) - (c + 1)) / 2 + 1
end