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

public class Main {
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        PrintWriter cout = new PrintWriter(System.out);

        int n = cin.nextInt();
        if(n % 2 == 0) {
            cout.println((n/2.0)/n);
        }
        else {
             cout.println(((n+1)/2.0)/n);
        }

        cout.close();
    }
}
/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