import java.util.*;

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