import java.util.Scanner;

public class Main {
  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);

    double n = sc.nextDouble();

    double odd = 0;
    double notOdd = 0;
    for (int i = 1; i <= n; i++) {
      if (i % 2 == 0) {
        notOdd++;
      } else {
        odd++;
      }
    }
    System.out.println(odd / n);
  }
}

/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