import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double ans = l/3;
        System.out.printf("%.12f\n",ans*ans*ans);

    }

} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double ans = l/3;
        System.out.printf("%.12f\n",ans*ans*ans);

    }

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

    } main {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double ans = l/3;
        System.out.printf("%.12f\n",ans*ans*ans);

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

    }

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

    }

} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double ans = l/3;
        System.out.printf("%.12f\n",ans*ans*ans);

    }

}