import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    }
} import java.util.*; util.* java public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    } main {
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long num = sc.nextLong(); num sc.nextLong() sc.nextLong sc double length = (double)num/3; length (double)num/3 (double)num 3 double ans = length*length*length; ans length*length*length length*length*length length length length System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    }
} public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    }
} Main
import java.util.*;
public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();

        double length = (double)num/3;
        double ans = length*length*length;

        System.out.println(ans);

        
    }
}