import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    }
} Main public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    } main {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    } long L; L try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        } {
            L = sc.nextLong();
        } Scanner sc = new Scanner(System.in) Scanner sc = new Scanner(System.in) new Scanner(System.in) L = sc.nextLong() L sc.nextLong() sc.nextLong sc double c = (double) L / 3; c (double) L / 3 (double) L 3 double M = c * c * c; M c * c * c c * c * c c c c System.out.println(String.format("%.8f",M)) System.out.println System.out System System.out String.format("%.8f",M) String.format String "%.8f" M String[] args args public class Main {
    public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    }
} public class Main {
    public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        long L;
        try (Scanner sc = new Scanner(System.in)) {
            L = sc.nextLong();
        }
        double c = (double) L / 3;
        double M = c * c * c;
        System.out.println(String.format("%.8f",M));
    }
}
