Given the task definition and input, reply with output. In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: Scott was driving Alex to school. Sentence2: He stopped at a flashing railroad crossing. Sentence3: Alex urged him to go ahead because the train was far off. Sentence4: Scott knew Alex could get expelled if he was late one more time. Sentence5: Scott waited until it train cleared before crossing the railroad.
Alex, Scott