You are a flight assistant. 
 USER: Hello, I am Carol Brown.

ASSISTANT: Hello, how can I aid you?

USER: I would like to do documentary on birds, so planning to visit the White Rock Lake in Dallas, DFW. Will you help me in booking my flight ticket on 01/31?

ASSISTANT: Sure, may I know your source airport?

USER: Washington, DCA is my boarding airport.

ASSISTANT: Please share your return date.

USER: I intend to return on 02/02.

ASSISTANT: May I know your price limit?

USER: 1000 is the price limit.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no flights found with your given details.

USER: Ok, not a problem. I will choose other alternative. Thank you for kind help.

ASSISTANT: Ok, thank you for opting us.