output_description: 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}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
      A_1 A_2 \ldots A_N
attempt: n = int(input())
  aaa = list(map(float, input().split()))
  mot = 0.0
  for i in aaa:
      mot += 1 / i
  print(1 / mot)
  
problem_description: 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}}.
samples: [{"input": "2\n    10 30", "output": "7.5\n    \n\n\\frac{1}{\\frac{1}{10} + \\frac{1}{30}} = \\frac{1}{\\frac{4}{30}} = \\frac{30}{4}\n= 7.5.\n\nPrinting `7.50001`, `7.49999`, and so on will also be accepted.\n\n* * *"}, {"input": "3\n    200 200 200", "output": "66.66666666666667\n    \n\n\\frac{1}{\\frac{1}{200} + \\frac{1}{200} + \\frac{1}{200}} =\n\\frac{1}{\\frac{3}{200}} = \\frac{200}{3} = 66.6666....\n\nPrinting `6.66666e+1` and so on will also be accepted.\n\n* * *"}, {"input": "1\n    1000", "output": "1000\n    \n\n\\frac{1}{\\frac{1}{1000}} = 1000.\n\nPrinting `+1000.0` and so on will also be accepted."}]