You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I am Barbara White from San Francisco. I want to go to Denver next week for my film shooting purpose. Can you please book a flight ticket from SFO to DEN?

ASSISTANT: I am happy to help you, please mention your trip dates to go.

USER: Thank you for your response, I want to take off on May 10 and please confirm my return ticket also on May 12.

ASSISTANT: Do you have any other requirements?

USER: I want a normal class flight so please check with that.

ASSISTANT: I am really sorry, there is no flight running on your route with your preferences.

USER: Oh! It's ok no problem. Thank you for your information.

ASSISTANT: Thanks for choosing us, have a good day.