import java.io.IOException;
import java.util.Scanner;

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

		int ans = Math.abs(x/l) + Math.abs(y/l) + 1;
		if (x % l != 0) ans += 1;
		if (y % l != 0) ans += 1;

		if (y < 0){
			ans += 1;
		}else if (x == 0){
			ans -= 1;
		}

		System.out.println(ans);
	}
}