import java.io.*;
import java.util.*;


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


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

