import java.util.*;
public class Robot{
	public static void main(String[] arg){
		int x,y,l,res=0;
		Scanner sc = new Scanner(System.in);
		x = sc.nextInt();
		y = sc.nextInt();
		l = sc.nextInt();
		if(y>= 0 && x != 0){
			res++;
		}else if(y<0){
			res = res+2;
		}
		if((x != 0) && (Math.abs(x)%l == 0)){
			res = res + (Math.abs(x)/l);
		}else if (x != 0){
			res = res + (Math.abs(x)/l)+1;
		}
		if((y != 0) && (Math.abs(y) % l == 0)){
			res = res + (Math.abs(y)/l);
		}else if (y != 0){
			res = res + (Math.abs(y)/l)+1;
		}
		System.out.println(res);
	}
}