Problem:
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

Solution in Rust (1.42.0) (judge verdict: Accepted)

use std::io;

fn main() {
    let mut buf = String::new();
    io::stdin().read_line(&mut buf).ok();

    let N = buf.trim().parse::<u32>().unwrap();
    let NN = buf.trim().parse::<f32>().unwrap();
    let ans = match N % 2 == 1 {
        true => (NN / 2.0 + 0.5) / NN,
        false => 0.5,
    };

    println!("{}", ans);
}