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)

/*   _ _ _                     
    | | | | ___  ___           
    | | | || . ||  _|          
    |_____||_  ||_|  _____     
             |_|    |_____|  */
// Time : 19/10/16
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define inf 0x3f3f3f3f
int main(){
#ifdef Wqr_
    freopen("in.txt","r",stdin);
#endif
    std::ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
    int n;
    cin >> n;
    int num = 0;
    for(int i = 1; i <= n; i++){
        if(i % 2) num++;
    }
    double ans = (double)num / n;
    cout << ans << endl;
    return 0;
}