Problem: 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}.

Examples

Input

4


Output

0.5000000000


Input

5


Output

0.6000000000


Input

1


Output

1.0000000000

Solution (in CPP):

Solution:
#include <iostream>
using namespace std;
int main(){
    int a; cin >> a;
    cout << (a%2!=0 ? (a+1)/2.0/a : a/2.0/a) << endl;
}