import java.util.*;

public class Main {

  public static void main(String[] args) {
    
     Scanner sc = new Scanner(System.in);
     int i = sc.nextInt();
  	 System.out.println((i + (i % 2 == 1 ? 1 : 0)) / 2d / i);
    
  }
  
}
  
/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