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

见题面

见题面