import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    } main {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc Double l = L/3.0; l L/3.0 L 3.0 System.out.println(l*l*l) System.out.println System.out System System.out l*l*l l*l*l l l l sc.nextLine() sc.nextLine sc String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        int L = sc.nextInt(); 
        Double l = L/3.0;

        System.out.println(l*l*l);
        sc.nextLine();
    }
}