You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Brain Martinez, I want to book a flight on 08/01 to meet my sister on her birthday. Can you book a flight ticket in economy class?

ASSISTANT: Sure, can I know your source and destination airport codes?

USER: My source point is Denver, CO-DEN and my destination point is Seattle, WA-SEA.

ASSISTANT: Ok, when will you return?

USER: I will return on 08/03.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Sorry, there are no flights found on given schedule.

USER: Thank you for the information.

ASSISTANT: Thank you for reaching us.