import java.util.Scanner;
 
public class Main {
    // Making a static main function
    public static void main(String[] args) {
      Scanner scanner = new Scanner(System.in);
      int num = scanner.nextInt();
      
      if (num % 2 ==0) 
        System.out.println("0.5");
      else {
        System.out.println((float)((num / 2) + 1) / num);
      }     
    }
}

/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