You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: Can you aid me in booking a flight ticket from SFO to DEN?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: Sure, I would like to go on June 09th and return back on June 11th.

ASSISTANT: Do you have any preferences?

USER: Make sure it is a single connecting flight.

ASSISTANT: May I know your name please?

USER: Myself Melissa Allen.

ASSISTANT: Sorry, there is no flight available with your requirements.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome, have a nice day.