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();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	}
} 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();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	}
} Main public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	} main {

		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextDouble(); L sc.nextDouble() sc.nextDouble sc double max = 0; max 0 double line = L / 3; line L / 3 L 3 BigDecimal bd = new BigDecimal(line * line * line); bd new BigDecimal(line * line * line) System.out.println(bd.toPlainString()) System.out.println System.out System System.out bd.toPlainString() bd.toPlainString bd String[] args args public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	}
} public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	}
} 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();
		double max = 0;
		double line = L / 3;

		BigDecimal bd = new BigDecimal(line * line * line);
		System.out.println(bd.toPlainString());
	}
}