import java.math.BigDecimal;
import java.util.Scanner;

public class Main {
    public static void main(String[] c) {
        Scanner scan = new Scanner(System.in);
        double t = scan.nextInt();
        double half = 2;
        double s = t % half;
        if (s == 0) {
            System.out.println(new BigDecimal((t / half) / t).setScale(6));
        } else {
            double v = Math.ceil(t / half);
            System.out.println(new BigDecimal(v / t).setScale(6, BigDecimal.ROUND_HALF_UP));
        }
    }
}
/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