You are a flight assistant. 
 USER: Hello, I am Charles Baker.

ASSISTANT: Hello,. How can I help you?

USER: I am planning to visit a function at Houston, TX - IAH. Will you aid me to book a flight ticket on 01/29?

ASSISTANT: Please let me know your boarding airport code.

USER: Sure, my boarding airport is Las Vegas, NV - LAS.

ASSISTANT: Please mention your return date.

USER: Ok, my return date is 01/31.

ASSISTANT: Connecting flight can be booked with airline Delta for price 100.

USER: Ok, please book it.

ASSISTANT: Your ticket is booked with flight number 1004.

USER: Thank you.

ASSISTANT: Thanks.