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.Numerics;
using System.Linq;

namespace c
{
    class Program
    {
        public static readonly long INF = 999999999999;
        public static readonly long MOD = 1000000007;

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

            if (n == 1) Console.WriteLine(1.0);
            else if (n % 2 == 0) Console.WriteLine(0.5);
            else Console.WriteLine(((n/2)+1)/(double)n);
        }
    }

    public class Scanner
    {
        public static string[] Scan() => Console.ReadLine().Split(' ');
        public static int[] IntScan() => Array.ConvertAll(Scan(), int.Parse);
        public static long[] LongScan() => Array.ConvertAll(Scan(), long.Parse);
        public static string[][] Scan(int n) => Enumerable.Repeat(0, n).Select(_ => Scan()).ToArray();
        public static int[][] IntScan(int n) => Enumerable.Repeat(0, n).Select(_ => IntScan()).ToArray();
        public static long[][] LongScan(int n) => Enumerable.Repeat(0, n).Select(_ => LongScan()).ToArray();

    }

    public class Ex
    {
        public static bool Chmin(ref int a, int b) { if (a > b) { a = b; return true; } return false; }
        public static bool Chmin(ref long a, long b) { if (a > b) { a = b; return true; } return false; }
        public static bool Chmax(ref int a, int b) { if (a < b) { a = b; return true; } return false; }
        public static bool Chmax(ref long a, long b) { if (a < b) { a = b; return true; } return false; }
        public static int[] SubArr(int[] arr, int begin, int n) { int[] a = new int[arr.Length]; Array.Copy(arr, begin, a, 0, n); return a; }
    }
}