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 {
	    	  long N = Long.parseLong(stdReader.readLine());
	    	  System.out.println((N/2)*(N/2));
	    	  } catch (IOException e) {
			e.printStackTrace();
	      }
	}	
}