import java.util.Scanner;

public class Test {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int x = sc.nextInt(), y = sc.nextInt(), t = sc.nextInt(), cnt = 0;
		if (x < 0) {
			x *= -1;
		}
		if (x > 0) {
			cnt++;
		}
		if (y < 0) {
			y *= -1;
			if (x > 0) {
				cnt++;
			} else {
				cnt += 2;
			}
		}
		cnt += x / t + y / t;
		if (x % t > 0) {
			cnt++;
		}
		if (y % t > 0) {
			cnt++;
		}
		System.out.println(cnt);
	}
}