import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	}

} 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();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	} main {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextDouble(); L sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc double l = L/3; l L/3 L 3 System.out.println(Math.pow(l,3)) System.out.println System.out System System.out Math.pow(l,3) Math.pow Math l 3 String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		sc.close();
		double l = L/3;
		System.out.println(Math.pow(l,3));
	}

}