You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Ryan Lee.

ASSISTANT: How may I render you?

USER: I am planning to celebrate my brother's birthday in San Francisco.So I would like to book a flight ticket. Can you please assist me in booking a flight ticket?

ASSISTANT: Sure, I can help you with it. Could you please provide your airport codes?

USER: My airport codes are from TX-DFW to CA-SFO.

ASSISTANT: On which dates would you like me to book a ticket?

USER: I would like to depart on 07/23 and return on 07/25.

ASSISTANT: Do you have any requirements?

USER: Yes, I need a halt. I can pay upto 1000.

ASSISTANT: Thanks for providing your details. Unfortunately there are no flights found on your scheduled dates.

USER: Ok, not an issue.

ASSISTANT: Thank you for contacting us.

USER: Thank you for your response.