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: Wrong Answer)


using System;

namespace _153232
{
    class Program
    {
        static void Main(string[] args)
        {
            string N = Console.ReadLine();
            double n = int.Parse(N);
            double a = -1;
            if (n == 1) { a = 1; }
            else if (n % 2 == 0) { a = 0.5; }
            else { a = (n + 1) / 2 / ((n - 1) / 2); }
            Console.WriteLine(a);
        }
    }
}