import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	} main {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double l = sc.nextDouble(); l sc.nextDouble() sc.nextDouble sc double ans = (l*l*l)/27; ans (l*l*l)/27 (l*l*l) l*l*l l l l 27 System.out.printf("%.10f", ans) System.out.printf System.out System System.out "%.10f" ans String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	}
} Main
import java.util.Scanner;


public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l = sc.nextDouble();
		double ans = (l*l*l)/27;
		System.out.printf("%.10f", ans);
	}
}
