import java.util.*;
import java.io.*;
import java.lang.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner (System.in);
		double n = sc.nextInt();
		double div = n;
		double count = 0;
		while (n>=1) {
			if (n%2 == 1) {
				count++;
			}
			n--;
		}
		double val = count / div;
		System.out.printf("%.10f \n", val);
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz