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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	}

} 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);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	} main {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc double d = l; d l double dd = d / 3; dd d / 3 d 3 double ddd = dd * dd * dd; ddd dd * dd * dd dd * dd * dd dd dd dd BigDecimal bi = BigDecimal.valueOf(ddd); bi BigDecimal.valueOf(ddd) BigDecimal.valueOf BigDecimal ddd System.out.println(bi) System.out.println System.out System System.out bi sc.close() sc.close sc String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	}

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

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int l = sc.nextInt();
		double d = l;
		double dd = d / 3;
		double ddd = dd * dd * dd;
		BigDecimal bi = BigDecimal.valueOf(ddd);
		System.out.println(bi);

		sc.close();
	}

}
