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 (1.15.1) (judge verdict: Accepted)

use std::io;       
     
fn main() {    
    let n: u32 = read().parse().unwrap();        
    let ans = ((n - (n / 2)) as f32 / n as f32);    
    println!("{}",ans);    
}                          
                           
     
fn read() -> String{    
    let mut s = String::new();    
    io::stdin().read_line(&mut s).ok();    
    s.trim().parse().ok().unwrap()    
}