# -*- coding: utf-8 -*-

X = int(input())
Y = int(input())
L = int(input())

x_count = abs(X)//L
x_count = x_count+1 if abs(X)%L>0 else x_count
y_count = abs(Y)//L
y_count = y_count+1 if abs(Y)%L>0 else y_count
y_lot = 0 if Y>=0 else 1
x_lot = 0 if X==0 else 1
print(x_count+y_count+y_lot+x_lot)