import java.util.Scanner;

public class No80 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int D = sc.nextInt();
		if( D % 2 != 0) {
			D -= 1;
		}
		int A = D / 4;
		System.out.println(A * (D/2 - A));
	}
}