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:
from decimal import Decimal
a = int(raw_input())
odds = []
for i in range(1, a + 1):
  if i % 2 != 0:
    odds.append(i)
x = Decimal(str(len(odds))) / Decimal(str(a))
print float(x)