Detailed Instructions: In this task, you're given the title of a story consisting of five sentences, numbered 1 through 5. Your job is to determine which two sentences need to be swapped sentences in order to make a story that makes complete sense and is befittingly titled. Indicate your answer using the numbers of the two sentences in order, such as '34' or '25'. The first digit refers to the sentence which should come first in the story.
Q: Title: The Teddy Bear. Sentence 1: She dropped David off at the house. Sentence 2: His mother helped him pack his bag. Sentence 3: David was going sleep at his grandparents' house. Sentence 4: David realized he hadn't packed his teddy bear. Sentence 5: David's mom went home to get his bear.
A:
13