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}.

Examples

Input

2
10 30


Output

7.5


Input

3
200 200 200


Output

66.66666666666667


Input

1
1000


Output

1000
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		 Scanner sc = new Scanner(System.in);
	        int N = sc.nextInt();
	        double ans = 0;
	        double A = 0;
	        double A1 = 0;
			
			for (int i=0; i<N; i++){
				A1 = sc.nextDouble();
				A += (1 / A1);
			}
			
			ans = 1/A;
			
			System.out.println(ans);
	}
}