Score : 200 points
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}}.
Input is given from Standard Input in the following format:
N A_1 A_2 \ldots A_N
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}.
2 10 30
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.
3 200 200 200
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.
1 1000
1000
\frac{1}{\frac{1}{1000}} = 1000.
Printing +1000.0
and so on will also be accepted.