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);
	    int n = sc.nextInt();
	    double m = n;
	    if(m % 2 ==0) {
	      System.out.println(0.5);
	    } else {
	      System.out.println((m+1)/(2*m));
	    }
	  }
	}