You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Helen Green.

ASSISTANT: How may I assist you today?

USER: Can you find a direct flight for me from LAS to DCA, to meet my school teacher.

ASSISTANT: May I know your travel dates to search flight for you?

USER: Sure, my trip dates are 02/05 and 02/07.

ASSISTANT: Sorry, I could not find any flight with your details.

USER: It's ok, thanks for your information.

ASSISTANT: It's my pleasure.