output_description: Print the circumference of the circle. Your output is considered correct if
  and only if its absolute or relative error from our answer is at most 10^{-2}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      R
attempt: pi = 3.1415926535
  r = int(input(""), 10)
  print(pi * (2 * r))
  
problem_description: Statement
  
  Print the circumference of a circle of radius R.
samples: [{"input": "1", "output": "6.28318530717958623200\n    \n\nSince we accept an absolute or relative error of at most 10^{-2}, 6.28 is also\nan acceptable output, but 6 is not.\n\n* * *"}, {"input": "73", "output": "458.67252742410977361942"}]