import java.util.*;
import static java.lang.Math.*;

public class Main {
	
	
  public static void main(String[] args) {
	  Scanner sc=new Scanner(System.in);
	  int D=sc.nextInt()/2;
	  int x=D/2;
	  int y=D-x;
	  System.out.println(x*y);
	  
  }}