You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I planned to meet my friend in LAS, can you please help me to book a flight ticket from BOS?

ASSISTANT: Sure, can I know the travel dates please?

USER: I prefer to travel on Jul 7 and Jul 9.

ASSISTANT: Do you have any requirements?

USER: I would like to depart in evening.

ASSISTANT: May I know your name please?

USER: I am Charles Adams.

ASSISTANT: Sorry, there are no flights available as per your request.

USER: Ok, no problem.

ASSISTANT: Thank you for approaching us.

USER: Thank you for your information.