package main

import (
	"fmt"
	"math"
)

func main() {
	var x, y, l float64
	_, _ = fmt.Scan(&x, &y, &l)

	mx := math.Ceil(math.Abs(x) / l)
	if x != 0 {
		mx += 1
	}

	my := math.Ceil(math.Abs(y) / l)
	if y < 0 {
		my += 2
		if x != 0 {
			my -= 1
		}
	}

	fmt.Println(int(mx + my))
}