import java.util.Scanner;
import java.util.stream.IntStream;

public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int n = Integer.parseInt(sc.next());
    int nums[] = IntStream.rangeClosed(1,n).toArray();

    double oddSum = 0;
    for (int i=0; i < n; i++) {
      if (nums[i] % 2 != 0) {
        oddSum = oddSum + 1;
      }
    }
    System.out.println(oddSum / 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