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;
using System.Linq;

class Program
{
    //static int[] dp;
    //static decimal[,,] dp;
    //static decimal N;
    static void Main(string[] args)
    {
        // 入力
        int[] input = Console.ReadLine().Split().Select(p => int.Parse(p)).ToArray();
        int N = input[0];

        decimal ret = 0;
        if(N%2==0)
        {
            ret = (decimal)0.5;
        }
        else
        {
            ret = (decimal)(N / 2 + 1) / (decimal)N;
        }

        Console.WriteLine(ret + "");
    }
}