You will be given a definition of a task first, then some input of the task.
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.

Title: The Contentious Employee. Sentence 1: He e-mailed Charles and the boss saying Regina was contentious. Sentence 2: But the coworker thought Regina was easy to work with. Sentence 3: Charles and his coworker switched shifts so he could work with Regina. Sentence 4: The coworker wanted to take a break and Regina started arguing. Sentence 5: Charles complained to his coworker that Regina was uncooperative.
Output:
15