import java.text.DecimalFormat;
import java.util.Scanner;

public class No48 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int x = s.nextInt();
        int y = s.nextInt();
        int l = s.nextInt();

        int turn = 0;
        turn += x != 0 && y < 0 ? 1 : 0;
        turn += x == 0 && y < 0 ? 2 : 0;
        turn += x != 0 && y != 0 ? 1 : 0;

        x = Math.abs(x);
        y = Math.abs(y);

        String steps = new DecimalFormat("")
            .format(Math.ceil((double) x / l) + Math.ceil((double) y / l) + turn);
        System.out.println(steps);
    }
}