You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Sandra Williams want to visit Los Angeles, can you book a ticket on 08/29 and 08/31?

ASSISTANT: I will help you with that. Can you please share your airport codes?

USER: Sure, I want to fly from DEN to LAX.

ASSISTANT: I am sorry to say that there is no flight found.

USER: That's ok, thank you.

ASSISTANT: Thank you.