import java.util.*;

public class Main{
	static Scanner sc = new Scanner(System.in);
	
	public static void main(String[] args){
		int n = sc.nextInt();
		int nOdd = (n % 2 == 0) ? n / 2 : (n + 1) / 2;
		double ans = 1.0 * nOdd / n;
		System.out.println(ans);
	}
}
/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