You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to celebrate my birthday at San Francisco, please help me in booking a ticket.

ASSISTANT: Sure, can I know the travel dates please?

USER: My travelling dates are 04/20 and 04/22.

ASSISTANT: Could you provide the airport codes please?

USER: My airport codes are IAH and SFO.

ASSISTANT: May I know your name please?

USER: My name is Emma Phillips.

ASSISTANT: There is a flight in UA airline with price 100, can I book it?

USER: Ok, please book my ticket.

ASSISTANT: Your ticket has been booked with flight number 1008.

USER: Thank you for your assistance.

ASSISTANT: You are welcome.