You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER:  As I am a scientist, I want to attend science festival with my students at Chicago. Can you do the reservation?

ASSISTANT: Sure, may I know your planned travel dates?

USER: Dates are 04/16 and 04/18.

ASSISTANT: May I know your source and destination codes?

USER: My airport codes are LAS-ORD.

ASSISTANT: Your good name please.

USER: Andrew Martinez here.

ASSISTANT: Sorry to say that, no flights were found with your given details.

USER: No problem, Thank you for kind service.

ASSISTANT: Thank you for opting us.