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Score : $100$ points

### 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.

### 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 $10^{-6}$.

### 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