#coding: utf-8
##yuki_48
import sys

x=int(raw_input())
y=int(raw_input())
l=int(raw_input())
if l==0:
 sys.exit()

if y>=0 and x==0: t=0
elif y>=0 and x!=0: t=1
elif y<0: t=2

absx=abs(x)
absy=abs(y)
d=absx/l+absy/l
if absx%l!=0: d+=1
if absy%l!=0: d+=1

res=t+d
print res