Instructions: 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.
Input: customer: Hi. 
 agent: Hello, how can I render you today? 
 customer: I am Melissa Philips. 
 agent: Ok. 
 customer: I would like to watch largest and most complete view of our milky way in galaxy wall at Grainier sky theatre which is located at Chicago, IL - ORD. Will you help me in booking a flight ticket with single connection? 
 agent: Sure, I would be happy to help you. 
 customer: Thank you. 
 __ 
 customer: My boarding airport code is WA - SEA. 
 agent: May I know how much do you want to spend on flight ticket? 
 customer: I can spend up to 5000. 
 agent: May I know when you have planned to travel? 
 customer: My planned travel dates are 10/02 and 10/04. 
 agent: Ok, please wait a moment, let me search a flight for you. 
 customer: Sure. 
 agent:  Thanks for your precious time. We found Spirit airline fare of 100. Shall I proceed for booking with single stopover flight? 
 customer: Ok. 
 agent: Your ticket has been confirmed with airline number 1029. 
 customer: Thank you. 
 agent: Thank you for choosing us.
Output:
agent: Can you please provide your take off airport code?