import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = Math.abs(sc.nextInt());
        int y = sc.nextInt();
        int k = sc.nextInt();
        int ans = 0;
        if (y < 0) {
            ans++;
            y = -y;
        }
        ans += (y + k - 1) / k;
        if (x != 0) {
            ans++;
        }
        ans += (x + k - 1) / k;
        System.out.println(ans);
    }
}