import java.util.Scanner;


public class Main {
	public static void main(String[] a) {
		Scanner s=new Scanner(System.in);
		int X=s.nextInt(),Y=s.nextInt(),L=s.nextInt(),H=(int)Math.ceil(Math.abs((float)X/L)),V=(int)Math.ceil(Math.abs((float)Y/L));
		System.out.println(H+V+(Y<0?2:X==0?0:1));
	}
}