You will be given a definition of a task first, then some input of the task.
In this task, you're given five sentences, numbered 1 through 5, and two options a and b for possible titles for the story. Your job is to choose the title that better fits the story. Indicate your choice by 'a' or 'b'.

Sentence 1: One halloween the streets were packed with children in costumes. Sentence 2: The porch lights were on waiting on the trick or treaters. Sentence 3: The children arrived at our house and candies were handed out. Sentence 4: The children's bags were full. Sentence 5: The children left running for the next house to trick or treat. Choices: a. Trick or Treat. b. Invention.
Output:
a