import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		int pencil = sc.nextInt();
		int w = 0;
		int h = 0;
		int area = 0;
		if (pencil < 4) {System.out.println(0);}
		else {
			int n = 0;
			while (pencil >= 2) {
				if (n%2==0) {w++;}
				else {h++;}
				pencil -= 2;
				area = w*h;
				n++;
			}
			System.out.println(area);
		}
	}
}