import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int x=sc.nextInt();
		int y=sc.nextInt();
		int l=sc.nextInt();

		int ans=0;
		
		ans+=(Math.abs(x)+l-1)/l;
		ans+=(Math.abs(y)+l-1)/l;
		if(y>=0&&x!=0){
			ans++;
		}else if(y<0){
			ans++;
			ans++;
		}
		System.out.println(ans);
	}
}