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 <iomanip>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <tuple>
#include <cstring>
#include <functional>
using namespace std;
typedef long long ll;
typedef pair<long long, long long> P;
#define rep(i, n) for(long long i=0; i<n; i++)
#define reps(i, s, e) for(long long i=s; i<e; i++)
#define repr(i, n) for(long long i=n-1; i>=0; i--)
#define reprs(i, s, e) for(long long i=e-1; i>=s; i--)

int main(){

    cin.tie(0);
    ios::sync_with_stdio(false);

    int n; cin >> n;

    if(n % 2 == 0){
        cout << 0.5 << endl;
    }
    else{
        cout << double((n+1)/2)/(n) << endl;
    }

    return 0;
}