import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    }
} Main public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    } main {
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) double l = scan.nextInt(); l scan.nextInt() scan.nextInt scan System.out.println(Math.pow(l / 3, 3)) System.out.println System.out System System.out Math.pow(l / 3, 3) Math.pow Math l / 3 l 3 3 scan.close() scan.close scan String[] args args public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    }
} public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    }
} Main
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner scan = new Scanner(System.in);
        double l = scan.nextInt();
        System.out.println(Math.pow(l / 3, 3));
        scan.close();
    }
}