import java.math.BigDecimal;
import java.util.Scanner;

/**
 * @author yoshizaki
 * ABC 159
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    }
} import java.math.BigDecimal; BigDecimal java.math import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    }
} Main public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    } main {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    } Scanner scanner= new Scanner(System.in); scanner new Scanner(System.in) BigDecimal l = new BigDecimal(scanner.nextInt()); l new BigDecimal(scanner.nextInt()) BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); edge l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP) l.divide l new BigDecimal(3) 10 BigDecimal.ROUND_HALF_UP BigDecimal BigDecimal.ROUND_HALF_UP BigDecimal answer = edge.pow(3); answer edge.pow(3) edge.pow edge 3 System.out.println(answer) System.out.println System.out System System.out answer String[] args args public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    }
} Main
import java.math.BigDecimal;
import java.util.Scanner;

/**
 * @author yoshizaki
 * ABC 159
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner= new Scanner(System.in);
        BigDecimal l = new BigDecimal(scanner.nextInt());
        BigDecimal edge = l.divide(new BigDecimal(3), 10, BigDecimal.ROUND_HALF_UP); 
        BigDecimal answer = edge.pow(3);
        System.out.println(answer);
    }
}