import java.util.*;
import java.io.*; 

public class Main {
	
	public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	}
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	
	public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	}
} Main public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	} main {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) float d = sc.nextFloat(); d sc.nextFloat() sc.nextFloat sc d = d/3 d d/3 d 3 System.out.println(d*d*d) System.out.println System.out System System.out d*d*d d*d*d d d d String... string string public class Main {
	
	public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	}
} public class Main {
	
	public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	}
} Main
import java.util.*;
import java.io.*; 

public class Main {
	
	public static void main(String... string) {
		Scanner sc = new Scanner(System.in);
		float d = sc.nextFloat();
		d = d/3; 
		System.out.println(d*d*d); 
	}
}