import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
public class Main {
	 public static void main(String[] args) {
	      BufferedReader stdReader =new BufferedReader(new InputStreamReader(System.in));
	      try {
	    	  int D = Integer.parseInt(stdReader.readLine());   	  
	    	  D /= 2;
	    	  int a = D/2;
	    	  int b = D-a;
	    	  System.out.println(a*b);
	      } catch (IOException e) {
			e.printStackTrace();
	      }
	}
}