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 Scala (2.11.7) (judge verdict: Runtime Error)

import scala.io.StdIn

object Main extends App {
  val Array(a, b) = StdIn.readLine().split(" ").map(_.toLong)
  val gcd_v = gcd(a, b)
  var ans = 0

  // (1l to gcd_v).foreach {i =>
  //   if ((isPrime(i)) && (gcd_v % i == 0l)) ans = ans + 1
  // }

  println(ans)
  

  def isPrime(i: Long) : Boolean = {
    if (i == 1l)
      true
    else if (i == 2l)
      true
    else
      !(2l to (i-1l)).exists(x => i % x == 0l)
  }

  def gcd(a: Long,b: Long): Long = {
    if(b ==0l) a else gcd(b, a%b)
  }
}