import java.math.BigInteger;
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    }
} import java.math.BigInteger; BigInteger java.math import java.util.*; util.* java import java.io.*; io.* java public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    }
} Main public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    } main {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    } Scanner in = new Scanner(System.in); in new Scanner(System.in) int L = in.nextInt(); L in.nextInt() in.nextInt in double side = (double) L / 3; side (double) L / 3 (double) L 3 System.out.println(side * side * side) System.out.println System.out System System.out side * side * side side * side * side side side side String[] args args public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    }
} public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    }
} Main
import java.math.BigInteger;
import java.util.*;
import java.io.*;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int L = in.nextInt();
      	double side = (double) L / 3;
        System.out.println(side * side * side);
    }
}