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 = Math.abs(s.nextInt());
        int y = Math.abs(s.nextInt());
        int l = s.nextInt();
        int turn = x != 0 && y != 0 ? 1 : 0;
        String steps = new DecimalFormat("")
            .format(Math.ceil((double) x / l) + Math.ceil((double) y / l) + turn);
        System.out.println(steps);
    }
}