Submission #405807

---

Source Code Expand

class AtCoder
  def initialize
    a, b = gets.chomp.split(' ').map(&:to_i)

    max_value = a - b

    0.upto(2) do |digit|
      max_value = [max_value, right_change(a, b, digit), left_change(a, b, digit)].max
    end

    puts max_value
  end

  def right_change(a, b, digit)
    b = "%03d" % [b]
    b[digit] = (digit == 0)? '1' : '0'

    a - b.to_i
  end

  def left_change(a, b, digit)
    a = "%03d" % [a]
    a[digit] = '9'

    a.to_i - b
  end
end

AtCoder.new

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Judge Result