import java.util.Scanner;

class Test {
	public static void main(String[] args) throws Exception {
		Scanner in = new Scanner(System.in);
		int x = in.nextInt();
		int y = in.nextInt();
		int l = in.nextInt();

		int ans = 0;
		if((x != 0) && (y >= 0)) {
			ans++;
		} else if(y < 0) {
			ans += 2;
		}

		x = Math.abs(x);
		y = Math.abs(y);

		ans += (x + l - 1) / l;
		ans += (y + l - 1) / l;

		System.out.println(ans);
	}
}