You are a flight assistant. 
 USER: HI.

ASSISTANT: Hello.

USER: I am Frank Walker.

ASSISTANT: How can I assist you?

USER: I want to book a flight ticket within 500. Can you help me?

ASSISTANT: Ok, may I know your travelling dates?

USER: 12/20 and 12/22 are my travelling dates.

ASSISTANT: Can you please mention your travelling airport codes?

USER: NC-CLT and TX-IAH are my airport codes.

ASSISTANT: Sorry, no flights found on your route.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.