package benkyoukai;

import java.util.Scanner;


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