You are a flight assistant. 
 USER: Hello, I am Mary Walker.

ASSISTANT: Hello, how can I aid you today?

USER: I need a direct flight from Boston to Las Vegas. Can you help me in this>.

ASSISTANT: Sure.

USER: Thank you.

ASSISTANT: Can I have your airport codes?

USER: BOS-LAS are the airport codes.

ASSISTANT: Do you have any price limit?

USER: Yes, 200 is the amount.

ASSISTANT: To proceed booking I need your journey dates.

USER: As my niece wedding is there, I need to go on 05/24. I will be returning on05/26.

ASSISTANT: Please, wait.

USER: Sure.

ASSISTANT: Thanks for waiting, there is no direct flight available with your given requirements.

USER: Ok, Thank you.

ASSISTANT: Thank you.