You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to book a flight from IAD to SFO?

ASSISTANT: Your travelling dates please?

USER: My travel dates are Mar 19th and 21st.

ASSISTANT: May I know connection limit please?

USER: I am fine with maximum one connection.

ASSISTANT: Do you have any other specifications?

USER: I want to depart in the evening and return back in the afternoon time.

ASSISTANT: May I know name please?

USER: My name is Michelle Clark.

ASSISTANT: I am sorry no flights found on your route.

USER: No problem, thank you.

ASSISTANT: Thank you for choosing us.