import java.util.*;
 
class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		System.out.println(Math.pow(sc.nextDouble()/3, 3));
	}
} import java.util.*; util.* java class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		System.out.println(Math.pow(sc.nextDouble()/3, 3));
	}
} Main public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		System.out.println(Math.pow(sc.nextDouble()/3, 3));
	} main {
		Scanner sc = new Scanner(System.in);
		System.out.println(Math.pow(sc.nextDouble()/3, 3));
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) System.out.println(Math.pow(sc.nextDouble()/3, 3)) System.out.println System.out System System.out Math.pow(sc.nextDouble()/3, 3) Math.pow Math sc.nextDouble()/3 sc.nextDouble() sc.nextDouble sc 3 3 String[] args args
import java.util.*;
 
class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		System.out.println(Math.pow(sc.nextDouble()/3, 3));
	}
}