input:
  question: A building has 10 floors. At the ground floor, 7 people enter the elevator.
    At the second floor, 3 people get off and 2 people enter. At the fourth floor,
    5 people get off and 2 people enter. At the seventh floor, 1 person gets off and
    3 people enter. Finally, at the tenth floor, everyone remaining in the elevator
    gets off. The question is, How many people were in the elevator when it started
    its journey, and how many total people exited the elevator by the end of its journey?
output: "At the start, the elevator has 7 people. After the second floor, there are
  4 people (7 - \n3 + 2). After the fourth floor, there are 6 people (4 - 5 + 2).
  After the seventh floor, \nthere are 7 people (6 + 1 - 5 + 3). Finally, at the tenth
  floor, there are 12 people (7 -\n1 + 3). Over the course of the journey, 35 people
  exited the elevator (7 - 4 + 6 + 7), \nand 12 people were in the elevator when it
  started its journey. The answer is 12."