import java.util.Scanner;

/**
 * Main
 */
public class Main {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);

        int N = s.nextInt();

        float res;

        if (N % 2 == 0)  res = (float) (1.0 / 2.0);
        else {
            int odd = N /2 +1;
            res = (float)odd / N;
        }

        System.out.println(res);
        s.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