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   ll          long long int
#define   sz          200010
#define   sc(a)       scanf("%lld",&a)
#define   sc2(a,b)    scanf("%lld %lld",&a,&b)
#define   py          printf("Yes\n")
#define   pn          printf("No\n")
using namespace std;



int main()
{

    ll n,a;

    cin>>n;
    a=n/2+n%2;

    double d=(a*1.0)/(n*1.0);
    printf("%0.10lf\n",d);

    return 0;
}