import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    } main {
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double N = sc.nextDouble(); N sc.nextDouble() sc.nextDouble sc double l = N/3; l N/3 N 3 System.out.println(l*l*l) System.out.println System.out System System.out l*l*l l*l*l l l l String[] args args public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    }
} public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double N = sc.nextDouble();
        double l = N/3;
        
        System.out.println(l*l*l);
    }
}