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 check(input_2:i32) -> bool{
let a = input_2 % 2;
if a==0 {
  return true;
}
else{
 return false;
}

}

fn main(){
let mut input = String::new();
io::stdin().read_line(&mut input).expect("something goes wrong");
let input = input.trim().parse().expect("something goes wrong");
let b = check(input);
if b==true {
println!(0.5);
}
if b==false{
let use_input:f32 = input as f32;
let answer:f32 = ((use_input+1.0)/2.0)/use_input;
println!("{}",answer);
}
}