import java.util.*;
import java.math.BigDecimal;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    }
} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    }
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    } main {
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double a = sc.nextDouble() / 3; a sc.nextDouble() / 3 sc.nextDouble() sc.nextDouble sc 3 double ans = a * a * a; ans a * a * a a * a * a a a a System.out.println(String.format("%.12f", ans)) System.out.println System.out System System.out String.format("%.12f", ans) String.format String "%.12f" ans String[] args args public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    }
} public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    }
} Main
import java.util.*;
import java.math.BigDecimal;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// 整数の入力
		double a = sc.nextDouble() / 3;
        double ans = a * a * a;
        System.out.println(String.format("%.12f", ans));
    }
}