import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	} main {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double s = (double) Integer.parseInt(sc.next()); s (double) Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc System.out.println(String.format("%.12f", Math.pow(s / 3, 3))) System.out.println System.out System System.out String.format("%.12f", Math.pow(s / 3, 3)) String.format String "%.12f" Math.pow(s / 3, 3) Math.pow Math s / 3 s 3 3 String[] args args public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	}
} public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	}
} Main
import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		double s = (double) Integer.parseInt(sc.next());
		System.out.println(String.format("%.12f", Math.pow(s / 3, 3)));

	}
}