import java.util.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	}
} import java.util.*; util.* java public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	} main {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double A = sc.nextInt(); A sc.nextInt() sc.nextInt sc double B = A/3.0; B A/3.0 A 3.0 System.out.println(B * B * B) System.out.println System.out System System.out B * B * B B * B * B B B B String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	}
} Main
import java.util.*;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double A = sc.nextInt();
		double B = A/3.0;
		System.out.println(B * B * B);
	}
}