import java.util.*;

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

public class Main{
    public static void main(String[] args){
	Scanner sc = new Scanner(System.in);
    double l = sc.nextDouble() / 3D;
	System.out.println(l * l * l);
	}
}