You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Could you please book a flight ticket with a direct flight to Boston as I want to attend my sister's marriage?

ASSISTANT: Sure, may I know your airport codes?

USER: My journey airport codes are from Denver, CO-DEN to Boston, MA-BOS.

ASSISTANT: May I know your trip dates?

USER: I will depart on 12/20 and return on 12/22.

ASSISTANT: Do you have price limit?

USER: My fare should be 500.

ASSISTANT: May I know your good name please?

USER: My name is Charles Rodriguez.

ASSISTANT: Unfortunately there is no flight on your details.

USER: No problem, thank you for the information.

ASSISTANT: Thanks for choosing us.