import java.util.Scanner;

class Main {

    public static void main(String[] args) {
        Scanner stdIn=new Scanner(System.in);

        double x=stdIn.nextDouble();
        double y=x/3.0;
        System.out.println(y*y*y);
        
        
    }

} import java.util.Scanner; Scanner java.util class Main {

    public static void main(String[] args) {
        Scanner stdIn=new Scanner(System.in);

        double x=stdIn.nextDouble();
        double y=x/3.0;
        System.out.println(y*y*y);
        
        
    }

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

        double x=stdIn.nextDouble();
        double y=x/3.0;
        System.out.println(y*y*y);
        
        
    } main {
        Scanner stdIn=new Scanner(System.in);

        double x=stdIn.nextDouble();
        double y=x/3.0;
        System.out.println(y*y*y);
        
        
    } Scanner stdIn=new Scanner(System.in); stdIn new Scanner(System.in) double x=stdIn.nextDouble(); x stdIn.nextDouble() stdIn.nextDouble stdIn double y=x/3.0; y x/3.0 x 3.0 System.out.println(y*y*y) System.out.println System.out System System.out y*y*y y*y*y y y y String[] args args
import java.util.Scanner;

class Main {

    public static void main(String[] args) {
        Scanner stdIn=new Scanner(System.in);

        double x=stdIn.nextDouble();
        double y=x/3.0;
        System.out.println(y*y*y);
        
        
    }

}