import java.util.*;
import java.math.BigDecimal;
import java.math.RoundingMode;

/**
 * @author yamato
 *
 */
public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	}

} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math import java.math.RoundingMode; RoundingMode java.math public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	}

} Main /**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	} main {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	} Scanner scanner = new Scanner(System.in); scanner new Scanner(System.in) int L = scanner.nextInt(); L scanner.nextInt() scanner.nextInt scanner double x = L; x L BigDecimal div = new BigDecimal(String.valueOf(27.0)); div new BigDecimal(String.valueOf(27.0)) BigDecimal x2 = new BigDecimal(String.valueOf(x)); x2 new BigDecimal(String.valueOf(x)) BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP); ans (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP) (x2.multiply((x2.multiply(x2))))
				.divide (x2.multiply((x2.multiply(x2)))) x2.multiply x2 (x2.multiply(x2)) x2.multiply x2 x2 div 7 RoundingMode.HALF_UP RoundingMode RoundingMode.HALF_UP System.out.println(ans.toPlainString()) System.out.println System.out System System.out ans.toPlainString() ans.toPlainString ans String[] args args public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	}

} public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	}

} Main
import java.util.*;
import java.math.BigDecimal;
import java.math.RoundingMode;

/**
 * @author yamato
 *
 */
public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scanner = new Scanner(System.in);
		int L = scanner.nextInt();
		double x = L;
		BigDecimal div = new BigDecimal(String.valueOf(27.0));
		BigDecimal x2 = new BigDecimal(String.valueOf(x));
		BigDecimal ans = (x2.multiply((x2.multiply(x2))))
				.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans.toPlainString());
		
	}

}