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:
# -*- coding: utf-8 -*-
N = int(raw_input())

count = 0.0

for i in xrange(1,N+1):
    if i%2 != 0:
        count += 1
    
print("{0:.10f}".format(count/N))