Problem: 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.

Constraints

* 1 \leq N \leq 100

Input

Input is given from Standard Input in the following format:


N


Output

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}.

Examples

Input

4


Output

0.5000000000


Input

5


Output

0.6000000000


Input

1


Output

1.0000000000

Solution (in PYTHON):

Solution:
import unittest
import sys

def count_odds_of_odd(n):
	#print n
	if n == 1:
		return float(1)
	else:
		odd_count = (n / 2) + (n % 2)
		#print odd_count
		odds_of_odd = float(odd_count) / float(n)
		return odds_of_odd

def read_input():
	#Read the input N
	n = int(sys.stdin.readline())
	return count_odds_of_odd(n)

class testMyCode(unittest.TestCase):
	def test_1(self):
		res = count_odds_of_odd(1)
		self.assertEqual(res, 1)
		res = count_odds_of_odd(4)
		self.assertEqual(res, 0.5)
		res = count_odds_of_odd(5)
		self.assertEqual(res, 0.6)

if __name__ == '__main__':
	res = read_input()
	print res
	#unittest.main()