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 C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
// using System.Collections.Generic;
// using System.Linq;
// using System.Text;

class Program
{
    static void Main()
    {
        string[] arr = Console.ReadLine().Split();
        int N;
        N = int.Parse(arr[0]);
        Console.WriteLine(Math.Floor((decimal)(N + 1) / 2) / N);
        return;
    }
}