Problem:
Score : 200 points

Problem Statement

Given is a sequence of N integers A_1, \ldots, A_N.

Find the (multiplicative) inverse of the sum of the inverses of these numbers, \frac{1}{\frac{1}{A_1} + \ldots + \frac{1}{A_N}}.

Constraints

1 \leq N \leq 100

1 \leq A_i \leq 1000

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 \ldots A_N

Output

Print a decimal number (or an integer) representing the value of \frac{1}{\frac{1}{A_1} + \ldots + \frac{1}{A_N}}.

Your output will be judged correct when its absolute or relative error from the judge's output is at most 10^{-5}.

Sample Input 1

2
10 30

Sample Output 1

7.5

\frac{1}{\frac{1}{10} + \frac{1}{30}} = \frac{1}{\frac{4}{30}} = \frac{30}{4} = 7.5.

Printing 7.50001, 7.49999, and so on will also be accepted.

Sample Input 2

3
200 200 200

Sample Output 2

66.66666666666667

\frac{1}{\frac{1}{200} + \frac{1}{200} + \frac{1}{200}} = \frac{1}{\frac{3}{200}} = \frac{200}{3} = 66.6666....

Printing 6.66666e+1 and so on will also be accepted.

Sample Input 3

1
1000

Sample Output 3

1000

\frac{1}{\frac{1}{1000}} = 1000.

Printing +1000.0 and so on will also be accepted.

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.stream.Stream;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String str  = sc.nextLine();
        String suuji = sc.nextLine();
        String[] astr = suuji.split(" "); //状況に合わせて
        Double tmp = 0.0;
        double ans = 0.0;
        Double hoge = 0.0;
        int[] in_data = Stream.of(astr).mapToInt(x->{
            try{
                return Integer.parseInt(x);
            }
            catch(Exception e){
                e.printStackTrace();
            }
            return 0;
        }).toArray();
        sc.close();

        for(int i=0;i<in_data.length;i++){
            hoge = (double)1 / in_data[i];
            tmp = tmp + hoge;
        }
        ans = 1/tmp;

        if(ans == (int) ans){
            System.out.println((int)ans);
        }else{
            System.out.println(ans);
        }
    }
}