You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I guide you?

USER: I am Charles Wilson. I have planned to meet my grand parents who resides in Las Vega. Could you please guide me in booking my flight ticket?

ASSISTANT: Sure, can I know your preferable dates?

USER: I am planning to start on 01/19 and return back on 01/21.

ASSISTANT: Can I know your airport codes?

USER: My airport codes are from HOU to LAS.

ASSISTANT: I am sorry, there are no flights available.

USER: Yes, please proceed. Thank you for the information.

ASSISTANT: Thank you, have a good day.