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:
num_odd = lambda x: x/2 if x % 2 == 0 else x/2 + 1 
 
import fileinput
for line in fileinput.input():
    try:
        N = int(line.strip())
    except:
        continue
 
    print(1.0 * num_odd(N) / N)