import java.util.Scanner;

public class No48 {

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

        int cnt = 0;

        int xMove = Math.abs(x / l);
        if (x % l != 0) xMove++;
        cnt += xMove;

        if (xMove != 0) cnt++;

        int yMove = Math.abs(y / l);
        if (y % l != 0) yMove++;
        cnt += yMove;

        System.out.println(cnt);

        sc.close();
    }

}