# -*- coding: utf-8 -*-
__author__ = 'yuuki'

N = 3
X,Y,L = [input() for i in range(N)]
i = 0
cnt = 0

if X != 0 and Y >= 0:
    cnt += 1
elif X == 0 and Y >= 0:
    cnt = 0
else:
    cnt += 2

X = abs(X)
Y = abs(Y)

if X % L ==0:
    cnt += (X / L)
else:
    cnt += (X / L)
    cnt += 1

if Y % L ==0:
    cnt += (Y / L)
else:
    cnt += (Y / L)
    cnt += 1
print cnt