You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Karen Hall. I want to book a ticket from Denver-DEN to San Francisco-SFO to meet my grandparents in San Francisco.

ASSISTANT: Sure, I am here to help you before that can I have your dates of travel?

USER: I am departing on 12/05 and return on 12/07.

ASSISTANT: Sorry, there is no flight for you Karen Hall according to your data.

USER: That' ok, thank you. I will check for other alternative.

ASSISTANT: Ok, thanks for choosing us.