import java.util.Scanner;
public class No48 {
	public static void main (String[] args){
	Scanner sc =new Scanner(System.in);
	int x=sc.nextInt();
	int y=sc.nextInt();
	int l=sc.nextInt();
	System.out.println((x!=0?Math.abs(x/l)+1:0)+(y==0?0:y>0?y/l:Math.abs(y/l)+2)+(x%l==0?0:1)+(y%l==0?0:1)-(x!=0&&y<0?1:0));
	}
}