import java.util.Scanner;

public class Main {

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

		int x, y, l;
		x = sc.nextInt();
		y = sc.nextInt();
		l = sc.nextInt();

		sc.close();

		int ans;
		if(x == 0) ans = 0;
		else ans = 1;

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

		System.out.println(x/l + y/l + ans);

	}

}