#!/usr/bin/env python3
#fileencoding: utf-8

walk = lambda dist, mv: dist//mv if dist%mv == 0 else dist//mv+1
turn = lambda x, y: 2 if y < 0 else (1 if x != 0 else 0)

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

print(walk(abs(Y), L) + walk(abs(X), L) + turn(X, Y))