You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Myself Charles Collins. I have to go DEN for attending a birthday party there, can you please book a direct flight ticket to Denver?

ASSISTANT: Sure, can you please tell your budget limit?

USER: My budget limit is 500.

ASSISTANT: May I know your departure date?

USER: My departure date is 02/07.

ASSISTANT: Can you please tell your origin location?

USER: Sure, my source airport is IAD.

ASSISTANT: Would you like to have return ticket too?

USER: Yes, please book my return ticket also on 02/09.

ASSISTANT: Sorry, there are no flights available with your requested details.

USER: Oh! It's ok no problem, I will go with another airline. Thank you for your information.

ASSISTANT: Thank you and have a nice day.