import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	}
} Main public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	} main {
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	} Scanner stdIn = new Scanner(System.in); stdIn new Scanner(System.in) double L = stdIn.nextInt(); L stdIn.nextInt() stdIn.nextInt stdIn double ans = 0; ans 0 ans = L / 3.0 ans L / 3.0 L 3.0 System.out.println(Math.pow(ans, 3)) System.out.println System.out System System.out Math.pow(ans, 3) Math.pow Math ans 3 stdIn.close() stdIn.close stdIn String[] args args public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	}
} public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		Scanner stdIn = new Scanner(System.in);
		double L = stdIn.nextInt();
		double ans = 0;

		ans = L / 3.0;

		System.out.println(Math.pow(ans, 3));
		stdIn.close();
	}
}
