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;
using System.Collections.Generic;

namespace csharp
{
    class Program
    {
        private const float V = 1.0f;

        static void Main(string[] args)
        {
            string lineStr;
            lineStr = Console.ReadLine();
            int n = int.Parse(lineStr);
            float ret;

            if (n % 2 == 0)
                ret = 0.5f;
            else
            {
                ret = (n / 2 + 1) * V / n;
            }

            Console.WriteLine(ret);

            return;
        }
    }
}