import java.util.*;
public class make{
	public static void main(String... args){
		Scanner scan = new Scanner(System.in);
		int D = scan.nextInt();
		if(D <= 3){
			System.out.println(0);
			return;
		}
		if(D%2!=0)D--;
		System.out.println(calc(D));
	}
	public static int calc(int d){
		int a = d/2;
		int h = a/2;
		int s = h+a%2;
		return h*s;
	}
}