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[]){//double 处理果盘
		Scanner in = new Scanner(System.in);
		int n = in.nextInt(),j;
		if (n % 2 == 0){
			j = n/2;
		}else{
			j = 1 + (n -1 )/2;
		}
		float x = (float)j/n;
		System.out.println(x);
		
	}
}