# -*- coding: utf-8 -*-
import math

X = input()
Y = input()
L = input()
Xt = math.ceil(abs(float(X)/float(L)))
Yt = math.cecil(abs(float(Y)/float(L)))
if X == Y == 0:
    ans = 0
elif Y == 0 and X != 0:
    ans = 1 + Xt
elif X == 0 and Y != 0:
    if Y > 0:
        ans = Yt
    elif Y < 0:
        ans = 2 + Yt
elif X != 0 and Y > 0:
    ans = 1 + Xt + Yt
elif X != 0 and Y < 0:
    ans = 2 + Xt + Yt
print int(ans)