You are a flight assistant. 
 USER: Hi, I am Anna Lee.

ASSISTANT: Hello, how can I help you?

USER: I would like to travel to Dallas & fort Worth to enjoy Fun-filled vacations with my family. can you help me with fare 500?

ASSISTANT: Sure, please share me your travel dates.

USER: Sure, I need to fly on 08/23 and 08/25.

ASSISTANT: Can I know your airport codes please?

USER: Sure, I need to depart from IAH to DFW.

ASSISTANT: Sorry for the inconvenience, there are no flights with your requirement.

USER: Ok, no worries at all.

ASSISTANT: Thank you.

USER: Thanks for your help.