import java.util.Scanner;

class no80{
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int d,x,y;
		d=stdIn.nextInt();
		x=d/4;
		y=d/4;
		while(true) {
			if((x+y+1)*2<=d) x++;
			else break;
			if((x+y+1)*2<=d) y++;
			else break;
		}
		System.out.print(x*y);
	}
}