import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	}

} Main public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	} main {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	} Scanner scn= new Scanner(System.in); scn new Scanner(System.in) int n= scn.nextInt(); n scn.nextInt() scn.nextInt scn double val = n*1.0/3; val n*1.0/3 n*1.0 n 1.0 3 double val1 = (val*val*val); val1 (val*val*val) val*val*val val val val System.out.println(val1) System.out.println System.out System System.out val1 String[] args args public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	}

} public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scn= new Scanner(System.in);
		int n= scn.nextInt();
		 double val = n*1.0/3;
		double val1 = (val*val*val);
		System.out.println(val1);
		

	}

}