import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;
import java.util.TreeSet;

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int D = sc.nextInt();
		
		final int D_2 = D / 2;
		
		System.out.println(D_2 % 2 == 0 ? (D_2 / 2) * (D_2 / 2) : (D_2 / 2) * (D_2 / 2 + 1));
	}
	
}