Problem Statement

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.

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}.

Constraints

• $1 \leq N \leq 100$

Sample Input 1

4

Sample Output 1

0.5000000000

There are four positive integers not greater than 4: 1, 2, 3, and 4. Among them, we have two odd numbers: 1 and 3. Thus, the answer is $\frac{2}{4} = 0.5$.

Sample Input 2

5

Sample Output 2

0.6000000000

Sample Input 3

1

Sample Output 3

1.0000000000

见题面 Input 部分

见题面 Output 部分