Instructions: In this task, you're given the title of a story consisting of five sentences, numbered 1 through 5. Your job is to arrange the sentences in order to make a story that makes complete sense and is apt for the title. Indicate your answer using the number of the sentences in order, such as '34152'.
Input: Title: No Return. Sentence 1: Crossing the river was seen as a threat to the city. Sentence 2: The general waited with his army, deciding what to do. Sentence 3: It was considered to be the border of the city. Sentence 4: The river flowed through the city from far in the north. Sentence 5: Caesar gathered his troops and crossed the Rubicon on his way to Rome.
Output:
43125