A, B, S = gets.split.map(&:to_i)
ans = if (A - S).abs <= (B - S).abs or S == 1
        (A - S).abs + S
      elsif A == 0
        (B - S).abs + S + 1
      else
        (B - S).abs + [(A - S).abs + A, S - 1 + A].min
      end
puts ans