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

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	}
} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	}
} Main public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	} main {
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int L = scan.nextInt(); L scan.nextInt() scan.nextInt scan BigDecimal a = BigDecimal.valueOf(L); a BigDecimal.valueOf(L) BigDecimal.valueOf BigDecimal L BigDecimal b = BigDecimal.valueOf(27); b BigDecimal.valueOf(27) BigDecimal.valueOf BigDecimal 27 BigDecimal sum = a.multiply(a.multiply(a)); sum a.multiply(a.multiply(a)) a.multiply a a.multiply(a) a.multiply a a BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP); ans sum.divide(b, 7, BigDecimal.ROUND_HALF_UP) sum.divide sum b 7 BigDecimal.ROUND_HALF_UP BigDecimal BigDecimal.ROUND_HALF_UP System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	}
} public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	}
} Main
import java.util.*;
import java.math.BigDecimal;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		int L = scan.nextInt();
		BigDecimal a = BigDecimal.valueOf(L);
		BigDecimal b = BigDecimal.valueOf(27);
		BigDecimal sum = a.multiply(a.multiply(a));
		BigDecimal ans = sum.divide(b, 7, BigDecimal.ROUND_HALF_UP);

		System.out.println(ans);
	}
}