import java.util.Scanner;


public class Main_yukicoder80 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int d = sc.nextInt();

        int xy = d / 2;
        int x = xy / 2;
        int y = xy - x;

        System.out.println(x * y);

        sc.close();
    }
}