import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	}
} Main public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	} main {
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	} Scanner as = new Scanner(System.in); as new Scanner(System.in) int n = Integer.parseInt(as.next()); n Integer.parseInt(as.next()) Integer.parseInt Integer as.next() as.next as System.out.println(Math.pow(n/3.0,3)) System.out.println System.out System System.out Math.pow(n/3.0,3) Math.pow Math n/3.0 n 3.0 3 String[] args args public class Main {
	public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	}
} public class Main {
	public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	}
} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args){
		Scanner as = new Scanner(System.in);
		int n = Integer.parseInt(as.next());
		System.out.println(Math.pow(n/3.0,3));
	}
}