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<vector>
#include<algorithm>
#include<string>
#include <cmath>
#include <limits>
#include <utility>
#include <map>
#include <iomanip>
#include <queue>
#include <cctype>
#include <stack>
#include <random>
#include <list>
#include <numeric>
#include <chrono>


#define rep(i,p,q) for(ll i = p;i < q;i++)
#define ll long long

using namespace std;

vector<vector<ll>> graph;
vector<ll> query;
vector<ll> ans;
vector<ll> visited;


const long long MAX_N = 1 << 17;

long long dat[2 * MAX_N - 1];

//142 A
int main(void) {
	ll a;
	cin >> a;
	if (a % 2 == 0)cout << fixed << setprecision(10) << 1 / (double)2 << endl;
	else cout << fixed << setprecision(10) << ((a + 1) / (double)2) / (double)a << endl;
}