You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Karen Moore.

ASSISTANT: How may I help you?

USER: I want to travel from CLT to DEN. Can you book a flight ticket for me?

ASSISTANT: Karen Moore, I am here to help you for this. When would you like to travel?

USER: I want to travel in the flight on Aug 10 and Aug 12.

ASSISTANT: Do you have any airline preference?

USER: I want to travel in normal-cost airline.

ASSISTANT: Is there any other requirements?

USER: I want to depart in evening time.

ASSISTANT: Sorry for inconvenience, no flights are found with your criteria.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you very much for contacting our agency.