import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int X = scan.nextInt();
		int Y = scan.nextInt();
		int L = scan.nextInt();
		scan.close();
		int ans = 0;
		if(Y < 0) {
			ans = 1;
			Y = - Y;
		}
		if(X != 0) {
			ans += 1;
			if(X < 0) {
				X = - X;
			}
		}
		ans += X / L + Y / L;
		if(X % L > 0) {
			ans += 1;
		}
		if(Y % L > 0) {
			ans += 1;
		}
		System.out.println(ans);
	}
}