#coding:utf-8

from math import ceil,fabs

X=float(input())
Y=float(input())
L=float(input())

if X==Y==0:
	print 0

if X==0 and Y!=0:
	if 0 < Y:
		print int(ceil(Y/L))
	elif Y < 0:
		print int(ceil(fabs(Y/L)))+2
elif X!=0 and Y==0:
	if 0 < X:
		print int(ceil(X/L))+1
	elif X < 0:
		print int(ceil(fabs(X/L)))+1

if X!=0 and Y!=0:
	if 0 < X and 0 < Y:
		print int(ceil(X/L)+ceil(Y/L))+1
	elif X < 0 and 0 < Y:
		print int(ceil(fabs(X/L))+ceil(Y/L))+1
	elif 0 < X and Y < 0:
		print int(ceil(X/L)+ceil(fabs(Y/L)))+2
	elif X < 0 and Y < 0:
		print int(ceil(fabs(X/L))+ceil(fabs(Y/L)))+2