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-----
2
10 30

-----Sample Output-----
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.

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