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.*;

class Main{
	public static void main(String[] $){
    Scanner in = new Scanner(System.in);
    double n = in.nextInt();
    double nam = 0;
    
    for(int i = 1; i <= n ; i++){
        if(i%2!=0){
            nam++;
        }
    }
	System.out.print(nam/n);
}
}