import java.util.Scanner;

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