import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	}
} import java.util.*; util.* java public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	} main {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextDouble(); L sc.nextDouble() sc.nextDouble sc double ans = L*L*L/27; ans L*L*L/27 L*L*L L*L*L L L L 27 System.out.println(String.format("%.12f", ans)) System.out.println System.out System System.out String.format("%.12f", ans) String.format String "%.12f" ans String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	}
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	}
} Main
import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextDouble();
		double ans = L*L*L/27;
		System.out.println(String.format("%.12f", ans));
	}
}