package no080;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int d = sc.nextInt();
		if (d <= 3) {
			System.out.println(0);
			return;
		}
		d = (d - d % 2) / 2;
		if (d%2 == 0) {
			System.out.println(d*d/4);
		}else{
			System.out.println((d/2)*(d/2+1));
		}
	}

}