output_description: Print the value of R_3.
  
  The output is considered correct if the absolute or relative error is at most
  10^{-6}.
  
  * * *
input_description: The input is given from Standard Input in the following format:
  
      
      
      R_1 R_2
attempt: print(eval("1/" + input().replace(" ", "+1/")) ** -1)
  
problem_description: Statement
  
  In an electric circuit, when two resistors R_1 and R_2 are connected in
  parallel, the equivalent resistance R_3 can be derived from the following
  formula:
  
    * \frac{1}{R_1} + \frac{1}{R_2} = \frac{1}{R_3}
  
  Given R_1 and R_2, find R_3.
samples: [{"input": "2 3", "output": "1.2000000000\n    \n\n* * *"}, {"input": "100 99", "output": "49.7487437186"}]