import java.util.*;
import java.math.*;
import java.io.*;
 
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;
		if(y >= 0 && x != 0) ans += 1;
		else if(y < 0 || x != 0) ans += 2;
		ans += Math.abs((y / l)) + (y % l != 0 && y != 0?1:0);
		ans += Math.abs((x / l)) + (x % l != 0 && x != 0?1:0);
		System.out.println(ans);
	}
}