You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I would like to depart in the evening. Could you please help me with booking a flight ticket?

ASSISTANT: Sure, may I know your airport codes?

USER: My airport codes are IAD and DEN.

ASSISTANT: On which dates you are travelling?

USER: I want to travel on dates Dec 5 and Dec 7.

ASSISTANT: May I know your name?

USER: I am Shirley Clark.

ASSISTANT: Sorry, there are no flights found on given dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching our service.