import java.util.*;
import java.math.BigDecimal;
public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  }
} import java.util.*; util.* java import java.math.BigDecimal; BigDecimal java.math public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  }
} Main public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  } main {
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  } Scanner sc =new Scanner(System.in); sc new Scanner(System.in) int L=sc.nextInt(); L sc.nextInt() sc.nextInt sc if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);} L==1 L 1 {System.out.println(0.0370370);} System.out.println(0.0370370) System.out.println System.out System System.out 0.0370370 if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);} L==2 L 2 {System.out.println(0.0740740);} System.out.println(0.0740740) System.out.println System.out System System.out 0.0740740 {
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);} int M=L*L*L; M L*L*L L*L*L L L L double m=M/27; m M/27 M 27 String X = BigDecimal.valueOf(m).toPlainString(); X BigDecimal.valueOf(m).toPlainString() BigDecimal.valueOf(m).toPlainString BigDecimal.valueOf(m) BigDecimal.valueOf BigDecimal m System.out.println(X) System.out.println System.out System System.out X String[] args args public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  }
} public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  }
} Main
import java.util.*;
import java.math.BigDecimal;
public class Main{
  public static void main(String[] args){
    Scanner sc =new Scanner(System.in);
    int L=sc.nextInt();
    if(L==1){System.out.println(0.0370370);}
    else if(L==2){System.out.println(0.0740740);}else{
    int M=L*L*L;
    double m=M/27;
    String X = BigDecimal.valueOf(m).toPlainString();
    System.out.println(X);}
  }
}
