user: Shelby was having a movie party for her birthday. She and her mom made a dozen bags of buttered popcorn and 10 bags of caramel popcorn. Her brother Alan took 3 bags of buttered popcorn and 1 bag of caramel popcorn for his friends. How many bags of popcorn does Shelby have left for the party? Let's think step by step and output the final answer after "####".
Answer: 18