import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigDecimal;

public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.PrintWriter; PrintWriter java.io import java.math.BigDecimal; BigDecimal java.math public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    }
} Main public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    } main {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    } PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) 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 average = (double)L/3; average (double)L/3 (double)L 3 out.println(BigDecimal.valueOf(average * average * average).toPlainString()) out.println out BigDecimal.valueOf(average * average * average).toPlainString() BigDecimal.valueOf(average * average * average).toPlainString BigDecimal.valueOf(average * average * average) BigDecimal.valueOf BigDecimal average * average * average average * average * average average average average out.flush() out.flush out out.close() out.close out br.close() br.close br String[] args args public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    }
} public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    }
} Main
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigDecimal;

public class Main {

    public static void main(String[] args) throws Exception {
        PrintWriter out = new PrintWriter(System.out);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int L = Integer.parseInt(br.readLine());
        double average = (double)L/3;
        out.println(BigDecimal.valueOf(average * average * average).toPlainString());
        out.flush();
        out.close();
        br.close();
    }
}