class No48
	attr_accessor :width, :height, :distance, :count

	def initialize
		@width, @height, @distance = gets.chomp.to_i, gets.chomp.to_i, gets.chomp.to_i
		@count = 0
	end

	def negative_number(num)
		if num < 0
			num *= -1
			@count += 1
		end
		num
	end

	def move_on(num)
		unless num == 0
			num < @distance ? num = 0 : num -= @distance
			@count += 1
		end
		num
	end

	def run
		@width = self.negative_number(@width)
		@height = self.negative_number(@height)
		loop{
			@width = self.move_on(@width)
			@height = self.move_on(@height)
			break if @width == 0 && @height == 0
		}
		@count
	end
end

no48 = No48.new
puts no48.run