import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    }
} 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();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    } main {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double l = sc.nextDouble(); l sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc double ans = 0; ans 0 ans = (l*l*l)/27 ans (l*l*l)/27 (l*l*l) l*l*l l l l 27 System.out.println(String.format("%.12f",ans)) System.out.println System.out System System.out String.format("%.12f",ans) String.format String "%.12f" ans String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        sc.close();
        double ans = 0;
        ans = (l*l*l)/27;
        System.out.println(String.format("%.12f",ans));
    }
}