You are a flight assistant. 
 USER: Hello. I am Steven Lopez.

ASSISTANT: Hello, how may I oblige you?

USER: Please book me a ticket with the fare of 200 to meet my friends.

ASSISTANT: Sure, may I know your depart and arrival dates?

USER: I have planned to travel on 08/12 and 08/14.

ASSISTANT: Could you provide your airport codes?

USER: My airport codes are from BOS to IAH.

ASSISTANT: Please, give me a minute.

USER: Ok.

ASSISTANT: Currently, there are no flights available.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for choosing us.