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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
class Program
{
    static void Main(string[] args)
    {
        int H, W, A, B;

        //string[] str = Console.ReadLine().Split(' ');//2つ以上のスペース区切り入力の取得
        string str = Console.ReadLine();
        int N = int.Parse(str);

        if (N % 2 == 0)
        {
            Console.Write("0.5");
        }
        else
        {
            double cal = N / 2;
            int kisuu = (int)Math.Ceiling(cal);
            double ans = (double)(kisuu + 1) / N;
            Console.Write(ans.ToString());
        }
    }
}