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 is given from Standard Input in the following format:

```
$N$
```

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 $10^{-6}$.

-   $1 \leq N \leq 100$

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 $\frac{2}{4} = 0.5$.