import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	}
} import java.util.Scanner; Scanner java.util public class Main{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	}
} Main public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	} main {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	} Scanner s = new Scanner(System.in); s new Scanner(System.in) int input = s.nextInt(); input s.nextInt() s.nextInt s double length = input/(double)3; length input/(double)3 input (double)3 System.out.println(length*length*length) System.out.println System.out System System.out length*length*length length*length*length length length length String[] args args public class Main{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	}
} public class Main{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	}
} Main
import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int input = s.nextInt();
		double length = input/(double)3;
		System.out.println(length*length*length);
	}
}