You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: I want to reserve my ticket from IAD to OAK to visit Oakland, can you please help me in booking?

ASSISTANT: Sure, may I know your good name?

USER: Ok, my name is Benjamin Walker.

ASSISTANT: Could you please share your preferred dates of journey?

USER: Sure, my planned dates of journey are from Aug, 16 to Aug, 18.

ASSISTANT: Do you have any specifications?

USER: Yes, I want to return in afternoon time.

ASSISTANT: Sorry, there are no flights available as per your requirements.

USER: Ok, not an issue. Anyways, thank you for your service.

ASSISTANT: Thank you for reaching us.