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: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define _GLIBCXX_DEBUG
#define debug(x) cerr << #x << ": " << x << '\n';

int main() {
  cout << fixed << setprecision(7);

  ios::sync_with_stdio(false);
  cin.tie(0);
  double n;
  int ans;
  ans = n;
  cin >> n;
  if (n == 1.0) {
    cout << 1.0000000000 << '\n';
  } else if (ans % 2 == 0.0) {
    cout << 0.5000000000 << '\n';
  } else {
    cout << ((n-1)/2)/n << '\n';
  }
}