import java.util.*;
import java.lang.*;
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);

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

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

		double L = sc.nextDouble();
		System.out.println((L/3)*(L/3)*(L/3));
	} main {
		Scanner sc = new Scanner(System.in);

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

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

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

		double L = sc.nextDouble();
		System.out.println((L/3)*(L/3)*(L/3));
	}
}