import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    }
} Main public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    } main {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double taiseki2 = sc.nextDouble(); taiseki2 sc.nextDouble() sc.nextDouble sc System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3) System.out.println System.out System System.out taiseki2/3 * taiseki2/3 * taiseki2/3 taiseki2/3 * taiseki2/3 * taiseki2 taiseki2/3 * taiseki2/3 taiseki2/3 * taiseki2 taiseki2/3 taiseki2 3 taiseki2 3 taiseki2 3 String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        double taiseki2 = sc.nextDouble();
        System.out.println(taiseki2/3 * taiseki2/3 * taiseki2/3);
    }
}
