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>
#define ii pair<int,int>
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define INF 100000000000000000
#define int long long int
#define modulo 1000000007
using namespace std;

int32_t main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    long double n;
    cin>>n;
    long double odd=0;
    for(int i=1;i<=n;i++){
        if(i%2)odd++;
    }
    cout<<setprecision(10)<<(long double)odd/n;
}