import java.util.Scanner;

/**
 * Maximum Volume
 * 
 * https://atcoder.jp/contests/abc159/tasks/abc159_c
 */
public class Main {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    }

} import java.util.Scanner; Scanner java.util public class Main {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    }

} Main static Scanner sc = new Scanner(System.in); sc new Scanner(System.in) public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    } main {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    } int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3))) System.out.println System.out System System.out String.format("%.6f", Math.pow(L / 3.0, 3)) String.format String "%.6f" Math.pow(L / 3.0, 3) Math.pow Math L / 3.0 L 3.0 3 String[] args args public class Main {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    }

} public class Main {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    }

} Main
import java.util.Scanner;

/**
 * Maximum Volume
 * 
 * https://atcoder.jp/contests/abc159/tasks/abc159_c
 */
public class Main {

    static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) throws Exception {
        int L = sc.nextInt();

        System.out.println(String.format("%.6f", Math.pow(L / 3.0, 3)));
    }

}
