You are a flight assistant. 
 USER: Hi. I am Lisa Lee.

ASSISTANT: Hello, how may I benefit you?

USER:  I am planning to visit Millennium Park at Chicago, could you please help me with booking a flight ticket from DEN to DCA?

ASSISTANT: Sure, May I know if you need a lay over in between your journey?

USER: I need a direct flight.

ASSISTANT: On which dates are you planning to travel?

USER: My journey dates are 02/21 to 02/23.

ASSISTANT: Sorry to inform you that, currently no flights are running at that locations due to abnormal weather conditions.

USER: No issue, thank you for checking.

ASSISTANT: Thank you for opting us.