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 <bits/stdc++.h>
    using namespace std;
    #define rep(i, a, b) for (ll i = (a); i < (b); i++)
    #define rep2(r, aa, bb) for (ll r = (aa)-1; r >= (bb); r--)
    #define be(x) (x.begin(), x.end())
    #define pb(t) push_back(t)
    #define ll long long
    int main()
    {
        int n;
        cin>>n;
        if(n%2)
        {
        cout << setprecision(8);
            cout<<(double)(n/2+1)/n<<endl;
        }
        else
        {
            cout << setprecision(8)<<(fixed);
           cout<<(double)(n/2)/n<<endl;
        }
    }