import java.math.BigDecimal;
import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double la = (l/3)*(l/3)*(l/3);
        System.out.println(BigDecimal.valueOf(la).toPlainString());
    }
} import java.math.BigDecimal; BigDecimal java.math import java.util.*; util.* java class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double la = (l/3)*(l/3)*(l/3);
        System.out.println(BigDecimal.valueOf(la).toPlainString());
    }
} Main public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double la = (l/3)*(l/3)*(l/3);
        System.out.println(BigDecimal.valueOf(la).toPlainString());
    } main {
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double la = (l/3)*(l/3)*(l/3);
        System.out.println(BigDecimal.valueOf(la).toPlainString());
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) double l = sc.nextDouble(); l sc.nextDouble() sc.nextDouble sc double la = (l/3)*(l/3)*(l/3); la (l/3)*(l/3)*(l/3) (l/3)*(l/3)*(l/3) (l/3) l 3 (l/3) l 3 (l/3) l 3 System.out.println(BigDecimal.valueOf(la).toPlainString()) System.out.println System.out System System.out BigDecimal.valueOf(la).toPlainString() BigDecimal.valueOf(la).toPlainString BigDecimal.valueOf(la) BigDecimal.valueOf BigDecimal la String[] args args
import java.math.BigDecimal;
import java.util.*;
class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        double l = sc.nextDouble();
        double la = (l/3)*(l/3)*(l/3);
        System.out.println(BigDecimal.valueOf(la).toPlainString());
    }
}