You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: Can you please book a flight ticket from DCA to SFO?

ASSISTANT: Sure, I will help you to book a flight ticket. Can you please share me your travelling dates?

USER: My trip is in Jan from 28th to 30th.

ASSISTANT: Ok, please share me your name.

USER: Mary Martinez here.

ASSISTANT: Ok, do you have any connection limit?

USER: I prefer a single connecting flight.

ASSISTANT: Ok, do you have any other specifications?

USER: No, thanks for asking.

ASSISTANT: Sorry, no flights are available on your route.

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

ASSISTANT: Welcome, have a nice day.