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)

#include<iostream>
#include<algorithm>
#include<math.h>
#include<vector>
#include<map>
#include<set>

using namespace std;
using ll = long long;

const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;
const double PI = 4.0 * atan(1.0);

#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rrep(i, a, n) for (int i = a; i <= (n); ++i)

int main() {
    int N; cin >> N;
    int tmp = (N + 1) / 2;
    double ans = (double) tmp / N;

    cout << ans << endl;
    return 0;
}