
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    }
    static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    }


}
// 2 4 6 8 10 12 import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    }
    static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    }


} Main public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    } main {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    } Scanner scn  = new Scanner(System.in); scn new Scanner(System.in) System.out.println(maxVolume(scn.nextDouble())) System.out.println System.out System System.out maxVolume(scn.nextDouble()) maxVolume scn.nextDouble() scn.nextDouble scn String[] args args static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    } maxVolume {
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    } return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2); l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2) l/3 * (l- l/3)/2 l/3 * (l- l/3) l/3 l 3 (l- l/3) l l/3 l 3 2 (l - l/3 - (l-l/3)/2) l - l/3 - (l-l/3)/2 l l/3 l 3 (l-l/3)/2 (l-l/3) l l/3 l 3 2 double l l public class Main {

    public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    }
    static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    }


} public class Main {

    public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    }
    static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    }


} Main

import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scn  = new Scanner(System.in);
        System.out.println(maxVolume(scn.nextDouble()));
    }
    static double maxVolume(double l){
        return  l/3 * (l- l/3)/2 *(l - l/3 - (l-l/3)/2);

    }


}
// 2 4 6 8 10 12
