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: Runtime Error)

data = gets.strip.split.map(&:to_i).sort
@step = 0

def next_step(data)
  a, b, c = data
  # 10 10 10
  if a == b && b == c
    return data
  end
  # 9 10 10
  if b == c && b - a == 1
    data[0] += 2
    data[1] += 1
    data[2] += 1
    @step += 2
    return data
  end

  # 8 10 10
  if b == c && b - a == 2
    data[0] += 2
    @step += 1
    return data
  end

  # 9 9 10
  if a == b && c - b == 1
    data[0] += 1
    data[1] += 1
    @step += 1
    return data
  end

  if a == b && c - b == 2
    data[0] += 2
    data[1] += 2
    @step += 2
    return data
  end

  # 7 9 10
  if c - b == 1 && b - a > 1
    data[0] += 1
    data[1] += 1
    @step += 1
    return data
  end

  # 5 8 10
  if b < c - 1 && a < b
    data[0] += 2
    @step += 1
    return data
  end

  if a < b && b < c
    data[0] += 1
    data[1] += 1
    @step += 1
    return data
  end

  # 1 8 10
  if b < c - 2
    data[1] += 2
    @step += 1
    return data
  end


end

while true
  a, b, c = data
  # p data
  # puts "step = #{@step}"
  if a == b && b == c
    break
  end
  data = next_step(data).sort
end

puts @step