You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: I am Melissa Carter.

ASSISTANT: Nice to meet you Melissa.

USER: I would like to attend my friend wedding at Denver, can you please help me to book a flight ticket from IAD to DEN?

ASSISTANT: Sure, tell me your travel dates please?

USER: Sure, my journey dates are May 12 and May 14.

ASSISTANT: Do you have any preferences?

USER: My departing time is afternoon.

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

USER: That's ok, thank you for your information.

ASSISTANT: Thank you.