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 JAVA):

Solution:
    import java.util.Scanner;
     
    public class Main {
    	public static void main(String[] args) {
    		Scanner sc = new Scanner(System.in);
    		
    		double n = sc.nextDouble();
    		System.out.println((Math.ceil(n/2))/n);
    	}
    }