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

public class Main {
	public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	}
} import java.util.*; util.* java import java.io.*; io.* java public class Main {
	public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	}
} Main public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	} main {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) double LLL = Double.parseDouble(br.readLine()); LLL Double.parseDouble(br.readLine()) Double.parseDouble Double br.readLine() br.readLine br double L = LLL/3; L LLL/3 LLL 3 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) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	}
} public class Main {
	public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	}
} Main
import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) throws IOException {
		
		// 入出力高速化 java.io.* とthrows IOExceptionを忘れずに
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		double LLL = Double.parseDouble(br.readLine());
		double L = LLL/3; 
		
		System.out.println(L*L*L);	
	}
}