You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I need to book a ticket from IAD to ORD. Could you book a ticket?

ASSISTANT: Sure, I am here to assist you. Please help me with your travel dates.

USER: Departure is May, 22 and return date is May, 24.

ASSISTANT: Thank you. Can you please tell me your name?

USER: I am Carolyn Rodriguez.

ASSISTANT: Thank you. Please let me know your class preference.

USER: I would like to prefer economy class.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your preferred travel dates.

USER: Thank you.

ASSISTANT: You are welcome and thank you for choosing us.