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++14 (GCC 5.4.1) (judge verdict: Accepted)

#pragma GCC optimize("-O3")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
void Main();
#ifdef ConanYu
#include "local.hpp"
#else
#define debug(...) do { } while(0)
int main() {
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  Main();
}
#endif

void Main() {
  int n; cin >> n;
  double ans = double((n + 1) / 2) / double(n);
  cout << fixed << setprecision(10) << ans << "\n";
}