import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int x = Integer.parseInt(br.readLine());
		int y = Integer.parseInt(br.readLine());
		int l = Integer.parseInt(br.readLine());

		int xl = (Math.abs(x) + l - 1) / l;
		int yl = (Math.abs(y) + l - 1) / l;

		int sum = 0;

		if (y >= 0) {
			if (x == 0) {
				sum = xl + yl;
			} else {
				sum = xl + yl + 1;
			}
		} else {
			sum = xl + yl + 2;
		}

		System.out.println(sum);

	}

}