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 n=0;
		if(y<0)n=2;
		else if(x!=0)n=1;
		System.out.println((Math.abs(x)+l-1)/l+(Math.abs(y)+l-1)/l+n);
	}
}