import java.util.Scanner;

public class No0048 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int X = sc.nextInt();
		int Y = sc.nextInt();
		int L = sc.nextInt();

		System.out.println(turnCount(X, Y) + aheadCount(X, L) + aheadCount(Y, L));
	}

	static int turnCount(int x, int y) {
		if (y >= 0) {
			if (x == 0) {
				return 0;
			}
			return 1;
		} else {
			return 2;
		}
	}

	static int aheadCount(int x, int l) {
		int cnt = (Math.abs(x) / l);
		if (x % l != 0) {
			cnt++;
		}
		return cnt;
	}
}