You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I need to book a flight ticket from DCA to DEN to enjoy fun filled vacations.

ASSISTANT: Sure, please share your journey dates?

USER: Sure, my journey dates are Jan 27 and Jan 29.

ASSISTANT: Do you have any specifications?

USER: I would prefer a depart time at evening. And I need a connected flight.

ASSISTANT: Are you looking for any class preferences?

USER: No.

ASSISTANT: Can I have your name to proceed?

USER: Sure, Susan Martin here.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thank you for your valuable time, unfortunately no flights available on that route.

USER: Ok, no issues. Thank you for your assistance.

ASSISTANT: Thank you for choosing us.