You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Dennis Martinez.

ASSISTANT: Nice to meet you Dennis.

USER: Help me in booking my flight ticket from Boston to Washington.

ASSISTANT: Sure, tell me your airport codes please?

USER: My airport codes will be BOS to DCA.

ASSISTANT: Now please share your travel dates?

USER: I want to depart on Nov 27th, my return date should be on Nov 29th.

ASSISTANT: Please wait. Thanks for waiting. But I am sorry to say that there are no flights available.

USER: That's ok, thank you.

ASSISTANT: Thank you.