import java.util.*;

public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    double l;
    double a;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    double l;
    double a;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    }
} Main // 変数一覧
    double l; l double a; a public static void main(String[] args) {
        Main main = new Main();
        main.run();
    } main {
        Main main = new Main();
        main.run();
    } Main main = new Main(); main new Main() main.run() main.run main String[] args args public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    } run {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) l = sc.nextDouble() l sc.nextDouble() sc.nextDouble sc sc.close() sc.close sc solve() solve private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    } solve {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    } a = l / 3.0 a l / 3.0 l 3.0 System.out.println(Math.pow(a, 3)) System.out.println System.out System System.out Math.pow(a, 3) Math.pow Math a 3 public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    double l;
    double a;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    }
} public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    double l;
    double a;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    double l;
    double a;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        l = sc.nextDouble();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a = l / 3.0;
        System.out.println(Math.pow(a, 3));
    }
}