import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    } main {
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double total_len = Double.valueOf(sc.next()); total_len Double.valueOf(sc.next()) Double.valueOf Double sc.next() sc.next sc System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0)) System.out.println System.out System System.out (total_len/3.0)*(total_len/3.0)*(total_len/3.0) (total_len/3.0)*(total_len/3.0)*(total_len/3.0) (total_len/3.0) total_len 3.0 (total_len/3.0) total_len 3.0 (total_len/3.0) total_len 3.0 String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double total_len = Double.valueOf(sc.next());
        System.out.println((total_len/3.0)*(total_len/3.0)*(total_len/3.0));
    }
}