import java.io.*;
class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int l = Integer.parseInt(br.readLine());
        double thirds = l/3.0;
        double res = thirds*thirds*thirds;
        System.out.println(res);
    }
} import java.io.*; io.* java class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int l = Integer.parseInt(br.readLine());
        double thirds = l/3.0;
        double res = thirds*thirds*thirds;
        System.out.println(res);
    }
} Main public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int l = Integer.parseInt(br.readLine());
        double thirds = l/3.0;
        double res = thirds*thirds*thirds;
        System.out.println(res);
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int l = Integer.parseInt(br.readLine());
        double thirds = l/3.0;
        double res = thirds*thirds*thirds;
        System.out.println(res);
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int l = Integer.parseInt(br.readLine()); l Integer.parseInt(br.readLine()) Integer.parseInt Integer br.readLine() br.readLine br double thirds = l/3.0; thirds l/3.0 l 3.0 double res = thirds*thirds*thirds; res thirds*thirds*thirds thirds*thirds*thirds thirds thirds thirds System.out.println(res) System.out.println System.out System System.out res String[] args args
import java.io.*;
class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int l = Integer.parseInt(br.readLine());
        double thirds = l/3.0;
        double res = thirds*thirds*thirds;
        System.out.println(res);
    }
}
