You are a flight assistant. 
 USER: Hello, Patricia Hill here.

ASSISTANT: Hello, how may I aid you today?

USER: I want to celebrate my sister's birthday in Denver on 06/15. Can you help me for booking with a direct flight?

ASSISTANT: Sure, could you please provide your other journey date?

USER: I would like to return on 06/17.

ASSISTANT: Ok, please provide your price limit?

USER: Make sure that the price limit is under 200.

ASSISTANT: Please mention your travelling locations?

USER: My source is San Francisco, CA - SFO. Destination is CO - DEN.

ASSISTANT: Do you have any preference connections?

USER: I have already provided my connection limit.

ASSISTANT: Ok, please hold a moment, let me check with the availability and get back to you.

USER: Sure.

ASSISTANT: Thanks for your valuable time, sorry, unfortunately no flights matching your criterion.

USER: Ok, no problem.

ASSISTANT: Thanks for connecting with us, have a nice day.

USER: Thanks for your help.