import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int len = sc.nextInt(); len sc.nextInt() sc.nextInt sc double wSide = (double)len/3; wSide (double)len/3 (double)len 3 double tSide = (double)len/3; tSide (double)len/3 (double)len 3 double hSide = (double)len/3; hSide (double)len/3 (double)len 3 double result = wSide*tSide*hSide; result wSide*tSide*hSide wSide*tSide*hSide wSide tSide hSide System.out.print(result) System.out.print System.out System System.out result sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int len = sc.nextInt();

		double wSide = (double)len/3;
		double tSide = (double)len/3;
		double hSide = (double)len/3;

		double result = wSide*tSide*hSide;

		System.out.print(result);
		sc.close();
	}
}
