You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: My name is David Green. I am planning to travel from OAK to BOS, could you help me with that?

ASSISTANT: Sure, may I know your travelling dates?

USER: Departure date is on 05/19 and return date is on 05/21.

ASSISTANT: The airline UA of flight number 1020 is available. Shall I proceed booking?

USER: Price limit should not exceed 500 and connections limit should be 1.

ASSISTANT: OK. This airline is matching all your requests. Shall I proceed booking?

USER: Please confirm the booking.

ASSISTANT: OK. Your ticket is booked.

USER: Thank you for the help.

ASSISTANT: Thank you.