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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"errors"
	"fmt"
)

func oddPercent(num int) float64 {
	var odds = make([]int, 0, num)
	if num >= 1 && num <= 100 {
		for i := num; i >= 0; i-- {
			if i%2 == 1 {
				odds = append(odds, i)
			}
		}
		p := float64(len(odds)) / float64(num)
		return p
	}
	panic(errors.New("No solution"))
}

func main() {
	var n int
	fmt.Scan(&n)
	fmt.Print(oddPercent(n))
}