import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    }
} import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.HashMap; HashMap java.util import java.util.Scanner; Scanner java.util public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    }
} Main public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    } main {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    } Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int l = scanner.nextInt(); l scanner.nextInt() scanner.nextInt scanner double d =(double) l/3; d (double) l/3 (double) l 3 double v = d*d*d; v d*d*d d*d*d d d d System.out.printf("%.12f\n",v) System.out.printf System.out System System.out "%.12f\n" v String[] args args public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    }
} public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    }
} Main
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int l = scanner.nextInt();

        double d =(double) l/3;
        double v = d*d*d;
        System.out.printf("%.12f\n",v);
       // System.out.println();
    }
}
