import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	}
} import java.util.*; util.* java import java.math.RoundingMode; RoundingMode java.math import java.math.BigDecimal; BigDecimal java.math public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double L = sc.nextInt(); L sc.nextInt() sc.nextInt sc BigDecimal ans = BigDecimal.valueOf(L*L*L); ans BigDecimal.valueOf(L*L*L) BigDecimal.valueOf BigDecimal L*L*L L*L*L L L L BigDecimal div = BigDecimal.valueOf(27); div BigDecimal.valueOf(27) BigDecimal.valueOf BigDecimal 27 ans = ans.divide(div,7,RoundingMode.HALF_UP) ans ans.divide(div,7,RoundingMode.HALF_UP) ans.divide ans div 7 RoundingMode.HALF_UP RoundingMode RoundingMode.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 sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	}
} Main
import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;
 
public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		double L = sc.nextInt();
		BigDecimal ans = BigDecimal.valueOf(L*L*L);
		BigDecimal div = BigDecimal.valueOf(27);
		ans = ans.divide(div,7,RoundingMode.HALF_UP);
		System.out.println(ans);
	}
}