Given the task definition and input, reply with output. 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: Marty Goes to the Dentist. Sentence 1: They had forgot about him and left him in the office! Sentence 2: The dentist told him he must have his tooth extracted. Sentence 3: The dentist put Marty to sleep. Sentence 4: When Marty woke up, the lights were off. Sentence 5: Marty had a pain in his tooth, so he decided to go to the dentist.
15