You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I need a direct flight to Las Angeles to visit my sister on her birthday. Can you book a flight ticket from Houston?

ASSISTANT: Sure, can you please share your journey dates?

USER: My travelling dates are 09/17 and 09/19.

ASSISTANT: May I know your airport codes please?

USER: My airport codes are TX - IAH to NV - LAS.

ASSISTANT: Can you please share your name?

USER: Emma Perez is my name.

ASSISTANT: Do you have any price limit?

USER: Price limit must be 5000.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry to say that we have not found any flights with your given details.

USER: Ok, no issues. Thanks for your information.

ASSISTANT: Thanks for choosing us.