import java.io.*;
import java.util.Scanner;
import java.util.Arrays;

public class Main{

    public static void main(String[] args){
        //START

        Scanner sc=new Scanner(System.in);
        int N=sc.nextInt();

        if(N%2==0){
            System.out.println("0.5000000000");
        }else{
            int s=N/2+1;
            double ans=(double)s/N;
            System.out.println(String.format("%.10f", ans));
        }

        //END
    }
}


/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