customer: Hello. 
 agent: Hello. How can I assist you? 
 customer: Myself Charles Wilson, I need to attend a metting at Denver.Could you help me by booking a ticket? 
 agent: Sure, can I know the travel dates please? 
 customer: I am willing to travel on 05/20 and again I will retrive on 05/22. 
 agent: Could you please provide the airport codes? 
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 agent: Sorry, there are no flights available on your route. 
 customer: Not a big deal, anyway thank you very much for your service. 
 agent: Thank you for approaching us.
customer: My departure and destination airport codes are ATL to DEN.