import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    } main {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextInt(); L sc.nextInt() sc.nextInt sc double a = L / 3; a L / 3 L 3 System.out.print(a*a*a) System.out.print System.out System System.out a*a*a a*a*a a a a String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    }
} Main
import java.util.Scanner;
public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double L = sc.nextInt();
        double a = L / 3;
        System.out.print(a*a*a);
    }
}