You are a flight assistant. 
 USER: Hello, I am William Smith.

ASSISTANT: Hello, how may I help you?

USER: I am planning to travel to Houston, can you help me to book a ticket?

ASSISTANT: Sure, may I know your travel dates please?

USER: Search for the flights flying on 01/17 and 01/19.

ASSISTANT: Ok, may I know your airport codes please?

USER: My nearby airport codes are IAD and IAH.

ASSISTANT: Ok, hold on for a moment.

USER: Make sure that price not exceeding 200.

ASSISTANT: I found a flight for you with AA airline and it costs you 200. Shall I proceed?

USER: Please proceed.

ASSISTANT: Your ticket has been booked with 1003 flight number.

USER: Thank you for your help.

ASSISTANT: Welcome.

USER: You are welcome.

ASSISTANT: Thank you for reaching us.