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: Full House. Sentence 1: Instead of boys they were having all girls. Sentence 2: His wife Lucy even had the names picked out for their future sons. Sentence 3: They were ecstatic to be expecting triplet boys. Sentence 4: On the day of the babies arrival they were told a mistake was made. Sentence 5: Robert always wanted a house full of sons.
15