import java.util.Scanner;

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();
        int c = (int)(Math.ceil(Math.abs(x) / (double)l) + Math.ceil(Math.abs(y) / (double)l));
        if (y < 0) {
            c += 2;
        } else if (x != 0) {
            c += 1;
        }
        System.out.println(c);
        scan.close();
    }
}