public IHttpActionResult Fibonacci(string n) { try { checked { if (!long.TryParse(n, out long param)) { return(BadRequest("The request is invalid.")); } else { //Generate the Fibonacci sequence. var value = helpers.Fibonacci(param); return(Ok(value)); } } } catch (OverflowException ex) { return(BadRequest("The request is invalid.")); } catch (Exception ex) { return(BadRequest("Error")); } }