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 a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    }
} 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 a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    } main {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double l = sc.nextDouble(); l sc.nextDouble() sc.nextDouble sc double a = l * l * l /27.0; a l * l * l /27.0 l * l * l l * l * l l l l 27.0 System.out.println(a) System.out.println System.out System System.out a String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    }
} 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 a = l * l * l /27.0;
        //BigDecimal ll = BigDecimal.valueOf(a);
        System.out.println(a);
    }
}