You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Patricia Lee here.

ASSISTANT: What help that you need from us right now?

USER: I would like to visit Denver to meet my grand parents over there, so can you please help me out with booking of a flight ticket to go there?

ASSISTANT: Yes, I will help in that ticket booking.

USER: Thank you.

ASSISTANT: May I know your planning trip dates?

USER: Sure, I am planning to move on 02/17 and I would like to return on 02/19.

ASSISTANT: May I know your source and destination airport codes?

USER: I want to travel from DCA to DEN.

ASSISTANT: Please wait for a moment.

USER: Sure, I will wait for your response.

ASSISTANT: As per your information, there is no flight obtained on your requested dates.

USER: Oh! So sad to hear. Anyway, I will choose another alternative to go there.

ASSISTANT: Is there any other trip dates?

USER: No. Thank you for the information.

ASSISTANT: Ok, thank you for utilizing our service. Have a nice day.

USER: Welcome.