output_description: Print the probability that a is odd. Your output will be considered correct
  when its absolute or relative error from the judge's output is at most
  10^{-6}.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N
attempt: #!/usr/bin/env python
  import string
  import sys
  from itertools import chain, dropwhile, takewhile
  
  INF = float("inf")
  
  
  def read(
      *shape, f=int, it=chain.from_iterable(sys.stdin), whitespaces=set(string.whitespace)
  ):
      def read_word():
          w = lambda c: c in whitespaces
          nw = lambda c: c not in whitespaces
          return f("".join(takewhile(nw, dropwhile(w, it))))
  
      if not shape:
          return read_word()
      elif len(shape) == 1:
          return [read_word() for _ in range(shape[0])]
      elif len(shape) == 2:
          return [[read_word() for _ in range(shape[1])] for _ in range(shape[0])]
  
  
  def readi(*shape):
      return read(*shape)
  
  
  def readi1(*shape):
      return [i - 1 for i in readi(*shape)]
  
  
  def readf(*shape):
      return read(*shape, f=float)
  
  
  def reads(*shape):
      return read(*shape, f=str)
  
  
  def arr(*shape, fill_value=0):
      if len(shape) == 1:
          return [fill_value] * shape[0]
      elif len(shape) == 2:
          return [[fill_value] * shape[1] for _ in range(shape[0])]
  
  
  def dbg(**kwargs):
      print(
          ", ".join("{} = {}".format(k, repr(v)) for k, v in kwargs.items()),
          file=sys.stderr,
      )
  
  
  def main():
      n = readi()
      print(sum(i % 2 == 1 for i in range(1, n + 1)) / n)
  
  
  if __name__ == "__main__":
      main()
  
problem_description: Statement
  
  Given is an integer N.
  
  Takahashi chooses an integer a from the positive integers not greater than N
  with equal probability.
  
  Find the probability that a is odd.
samples: [{"input": "4", "output": "0.5000000000\n    \n\nThere are four positive integers not greater than 4: 1, 2, 3, and 4. Among\nthem, we have two odd numbers: 1 and 3. Thus, the answer is \\frac{2}{4} = 0.5.\n\n* * *"}, {"input": "5", "output": "0.6000000000\n    \n\n* * *"}, {"input": "1", "output": "1.0000000000"}]