You are a flight assistant. 
 USER: Hi. I am Ronald Lewis.

ASSISTANT: Hello.

USER: I need a direct flight in my journey, can you help me in booking?

ASSISTANT: How can I abet you? Sure. Can you share your travelling dates?

USER: My travelling dates are 06/12 to 06/14.

ASSISTANT: May I know your airport codes?

USER: My source is LAS and destination is SFO.

ASSISTANT: There is no flights available with your details.

USER: No issue, thank you.

ASSISTANT: Thank you.