import java.util.*;

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