import java.util.Scanner;

public class No00000048_Main {

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		int x = scan.nextInt();
		int y = scan.nextInt();
		int l = scan.nextInt();

		int cnt = 0;
		if(x != 0 || y != 0) {
			if(y >= 0) {
				if(x != 0) {
					cnt += 1;
				}
			} else {
				cnt += 2;
			}
			cnt += (Math.abs(x) / l) + (Math.abs(x) % l == 0 ? 0 : 1);
			cnt += (Math.abs(y) / l) + (Math.abs(y) % l == 0 ? 0 : 1);
		}

		System.out.println(cnt);

		scan.close();

	}

}