import java.util.*;
import java.text.DecimalFormat;

public class Main {
  public static void main(String[] args) throws Exception {
    Scanner scanner = new Scanner(System.in);
    int N = scanner.nextInt();
    scanner.close();
    
    DecimalFormat df = new DecimalFormat("0.0000000000");
    System.out.println(df.format((N % 2 == 0) ? 1.0/2 : 1.0*((N / 2) + 1) / 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