You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Andrew Edwards.

ASSISTANT: How can I assist you?

USER: I have planned a tour with my friends in Washington DC. Can you please help me with flight ticket booking?

ASSISTANT: Sure, may I know your airport codes?

USER: Airport codes of my locations are CLT and DCA.

ASSISTANT: Ok, could you provide me your travelling dates?

USER: My travelling dates will be on 04/02 and 04/04.

ASSISTANT: Ok, wait for a minute.

USER: Sure.

ASSISTANT: Sorry, Andrew no flights found for this search.

USER: Oh! It's ok. Thank you for your help.

ASSISTANT: Ok, thank you for contacting us.