def main():
	x = int(input())
	y = int(input())
	l = int(input())

	count = 0

	if(y < 0): #南方向に進む場合
		count += 2 

	while(y > 0): #南北に進む
		y -= l
		count += 1

	if(x != 0):
		count += 1

	while(x > 0): #東西に進む
		y -= l
		count += 1
	print(count)

if __name__ == '__main__':
	main()