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

    if (a - s).abs <= (b - s).abs
      puts (a - s).abs + s
    else
      if (a - s).abs >= (s - 1)
        puts (b - s).abs + (s - 1) + (a - s).abs + 1
      else
        puts (b - s).abs + (a - s).abs + a
      end
    end
  end
end

Yukicoder.new