import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l=sc.nextDouble();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	}
} import java.math.BigDecimal; BigDecimal java.math 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();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l=sc.nextDouble();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	} main {
		Scanner sc = new Scanner(System.in);
		double l=sc.nextDouble();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

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

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l=sc.nextDouble();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	}
} Main
import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double l=sc.nextDouble();

		BigDecimal volume = new BigDecimal(Math.pow(l/3, 3));

		System.out.println(volume);
	}
}