package main

import (
	"fmt"
	"math"
)

func resolve(X, Y, L int) int {
	ret := 0
	flg := 0
	dx := int(math.Ceil(math.Abs(float64(X)) / float64(L)))
	dy := int(math.Ceil(math.Abs(float64(Y)) / float64(L)))

	if Y > 0 {
		ret += dy
	}
	if X != 0 {
		ret += 1 + dx
		flg = 1
	}
	if Y < 0 {
		ret += 2 + dy - flg
	}
	return ret
}

func main() {
	var X, Y, L int
	fmt.Scanf("%d\n%d\n%d\n", &X, &Y, &L)
	fmt.Println(resolve(X, Y, L))
}