Definition: You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").
Input: Paragraph- Sent 1: The bar was manned by an expensive humanoid robot.
Sent 2: It turned toward Sarah's wave and acknowledged her with a nod, moments later setting a fluted glass of sparkling liquid in front of her.
Sent 3: I marveled at the robot's smoothness and coordination.
Sent 4: Clearly, it was a high-end model.
Sent 5: Sarah transferred the glass to my free hand and pulled me away from the bar for more introductions, with Alexis trailing after us.
Sent 6: I spent the evening listening, mostly.
Sent 7: Listening and stuffing my face with all the bits of fine food provided.
Sent 8: No one minded; Sarah's inner circle was content to fill our circle of couches with plenty of chatter.
Sent 9: Ray, a plump man who was grey where he wasn't bald.
Sent 10: Zheng, short and dark and lean, with a very intense gaze.
Sent 11: He made me a little uncomfortable.
Sent 12: Kishori, petite, her hair strung out in a series of braids that reached nearly to her waist.
Sent 13: I categorized them based on their appearances, hoping I'd be able to pick them out of the crowd again later.
Sent 14: Most of their chatter was meaningless to me—stories of day-to-day activities, how so-and-so had been seen in so-and-so's table at lunch and my wasn't that a surprise, and why hadn't the chef concocted this delectable a selection of appetizers for the dance the other night, but of course those rolled meat pastries reminded one of the pastries back on Earth, didn't they, and this was somehow an interesting fact.
Sent 15: After the first half-hour, I stopped expending effort to keep names and stories and gossip straight.
Sent 16: I wasn't learning anything useful.
Sent 17: I could have started asking questions, but I wanted to get my bearings first.
Sent 18: Tonight was for observation.
Sent 19: I didn't bother trying to seek out a different group of potentially more interesting people, though.
Sent 20: They all looked the same: clusters of social butterflies surrounded by the less apt, the hangers-on, the circle with whom the gossip was shared. 
Question: How many people did the narrator spend time with?.
Output:
2, 5, 9, 10, 12.