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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <iostream>
#define FAST ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#include <algorithm>
#include <bits/stdc++.h>
#define MOD 1000000000000000000
#define ll long long
#define mm(arr) memset(arr, 1, sizeof(arr))
#define scanArray(a,n) for(ll i = 0; i < n; i++){cin >> a[i];}
using namespace std;
int main(){
    FAST
     double n; cin >> n;
     double cnt;
     for(int i=1; i<=n; i++){
        if(i%2!=0){
            cnt++;
        }
     }
     cout << cnt/n << endl;
    return 0;
}