package no048;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long x = sc.nextInt();
		long y = sc.nextInt();
		long l = sc.nextInt();
		long ans = 0;
		if (y >= 0) {
			if (x != 0) {
				ans += 1;
			}
		}else{
			ans += 2;
		}
		if (Math.abs(x) > 0) {
			ans += (Math.abs(x) - 1) / l + 1;
		}
		if (Math.abs(y) > 0) {
			ans += (Math.abs(y) - 1) / l + 1;
		}
		System.out.println(ans);
	}

}