You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: Can you help me to book a flight on 04/11 and 04/13?

ASSISTANT: Sure, we are here to help you.

USER: Thank you.

ASSISTANT: Can you share me your source point and destination point?

USER: My preferred airport codes are LAS and ATL.

ASSISTANT: Do you have any other specifications?

USER: I prefer economy class ticket.

ASSISTANT: May I know your name?

USER: I am Helen Lewis from Las Vegas.

ASSISTANT: Ok, wait for some time.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting there is no flight found on your details.

USER: No issues, thank you for your time.

ASSISTANT: Thank you.