package main

import (
	"fmt"
)

func abs(i int) int {
	if i < 0 {
		return -i
	}
	return i
}

func foot(l, d int) int {
	if l%d > 0 {
		return l/d + 1
	}
	return l / d
}

func main() {
	var X, Y, L, task int
	fmt.Scan(&X, &Y, &L)
	if X != 0 {
		task++
		if Y < 0 {
			task++
		}
	} else if Y < 0 {
		task += 2
	}

	task += foot(abs(X), L)
	task += foot(abs(Y), L)

	fmt.Println(task)
}