You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I serve you today?

USER: Brian Phillips here. I'm planning to visit my uncle's home, can you please book a ticket from DCA to SFO?

ASSISTANT: Sure, let me know your travel dates please?

USER: Yes, my planned departure and return travel dates are 29th and 31st of March.

ASSISTANT: Do you need any lay by in between your journey?

USER: Yes, my maximum connection should be 1.

ASSISTANT: Ok, is there any class preference?

USER: No but I want to depart on the evening.

ASSISTANT: Do you need any airline preference?

USER: No, I'm ok with any airlines.

ASSISTANT: Please wait for a while.

USER: Sure, take your own time.

ASSISTANT: Sorry to inform you that there are no flight services available on your given those dates.

USER: Oh! That's ok, thank you for giving the information anyways.

ASSISTANT: Thanks for reaching us, have a nice day.