import java.text.DecimalFormat;
import java.io.*;
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    }
} import java.text.DecimalFormat; DecimalFormat java.text import java.io.*; io.* java import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    } main {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) PrintWriter pw = new PrintWriter(System.out); pw new PrintWriter(System.out) DecimalFormat df = new DecimalFormat("0.00000000"); df new DecimalFormat("0.00000000") int L = Integer.parseInt(sc.next()); L Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc double d = (double) L/3.0; d (double) L/3.0 (double) L 3.0 double ans = d*d*d; ans d*d*d d*d*d d d d pw.println(df.format(ans)) pw.println pw df.format(ans) df.format df ans pw.flush() pw.flush pw String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    }
} Main
import java.text.DecimalFormat;
import java.io.*;
import java.util.*;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        PrintWriter pw = new PrintWriter(System.out);
//        sc.useDelimiter("\n");
        DecimalFormat df = new DecimalFormat("0.00000000");
        
        int L = Integer.parseInt(sc.next());
        double d = (double) L/3.0;
        double ans = d*d*d;
        pw.println(df.format(ans));
        
        pw.flush();
    }
}