import java.util.Scanner;

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