You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Barbara Thomas here.

ASSISTANT: How can I assist you?

USER: Can you help me to find a flight from IAD? Where my price limit is 500 only.

ASSISTANT: Sure, I will help you that.

USER: My travelling dates are 07/22 and 07/24.

ASSISTANT: May I know your destination and travelling dates?

USER: My destination airport is DCA.

ASSISTANT: Ok, wait a moment. I am sorry to say that there is flight found.

USER: Oh! that's fine. Thank you for your help.

ASSISTANT: Thank you for reaching us.