import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int taiseki = sc.nextInt(); taiseki sc.nextInt() sc.nextInt sc double taiseki2 = (double)taiseki; taiseki2 (double)taiseki double ans = taiseki2/3; ans taiseki2/3 taiseki2 3 double ans2 = ans * ans * ans; ans2 ans * ans * ans ans * ans * ans ans ans ans System.out.println(ans2) System.out.println System.out System System.out ans2 String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int taiseki = sc.nextInt();
        double taiseki2 = (double)taiseki;
        double ans = taiseki2/3;
        double ans2 = ans * ans * ans;
        System.out.println(ans2);
    }
}
