You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be your guide for today?

USER: I am Robert Brown. I have to go Denver to meet my friend over there so please help me with flight ticket booking from Chicago.

ASSISTANT: Sure, I Will help you with that Robert Brown. Can you Please provide your planned dates of journey?

USER: Thank you. I have planned to travel on dates of Dec 24 and Dec 26.

ASSISTANT: Do you have any preferences about your journey?

USER: Yes, I would like to depart in the evening time.

ASSISTANT: May I know if you want any specific time for your return journey?

USER: No, I am ok with any time in returning.

ASSISTANT: As per your requirements Robert Brown, there are no flights which can travel to your region.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: You are welcome, thank you for reaching us.