
import java.util.Scanner;

public class Main {
	public static void main(String args[]){
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		double ans=1.*((n+1)/2)/n;
		System.out.print(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