import java.util.Scanner;

public class Main {

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

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

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

	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		double N = input.nextDouble();
		double dimension = N/3;
		System.out.println(dimension*dimension*dimension);
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner input = new Scanner(System.in);
		double N = input.nextDouble();
		double dimension = N/3;
		System.out.println(dimension*dimension*dimension);
	}
}