In this task, you're given a dialogue between a customer and a flight booking agent with a gap in the conversation. Your job is to find the answer of the previous dialogue. Avoid using irrelevant extra information while creating the answer. The answer should be relevant to the question before the blank. If you fill the blank with a question, it should have an answer from the agent in the given dialogue. Fill the gap marked with underline.
Q: customer: Hello. Ruth Thompson here. 
 agent: Hello, how can I help you? 
 customer: My preferable dates for travel are 09/15 to 09/17. Can you reserve a flight ticket to Oakland for my family vacation? 
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 customer: My airport codes for boarding the flight are DTW to OAK. 
 agent: Please wait a while. 
 customer: Ok. 
 agent: There is a flight with connection limit 1 and fare 100, shall I proceed for booking? 
 customer: I am fine with the fare. You can book it. 
 agent: Your ticket is booked, flight number 1012. 
 customer: Thank you. 
 agent: Thank you for opting us.
A: 
agent: May I know your desired airport codes please?