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

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	}
} import java.math.BigDecimal; BigDecimal java.math import java.math.RoundingMode; RoundingMode java.math import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	}
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	} main {
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) BigDecimal l = new BigDecimal(scan.next()); l new BigDecimal(scan.next()) l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP) l l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP) l.divide l new BigDecimal("3") 6 RoundingMode.HALF_UP RoundingMode RoundingMode.HALF_UP System.out.println(l.multiply(l).multiply(l)) System.out.println System.out System System.out l.multiply(l).multiply(l) l.multiply(l).multiply l.multiply(l) l.multiply l l l String[] args args public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	}
} public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	}
} Main
import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.Scanner;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		BigDecimal l = new BigDecimal(scan.next());
		l = l.divide(new BigDecimal("3"), 6, RoundingMode.HALF_UP);

		System.out.println(l.multiply(l).multiply(l));
	}
}