Definition: In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.
Input: Article: For a commuter rushito catch a train, a minute can mean the difference between dinner with the family and foods in the microwave. What most passengers don't realize is that their minute is already there.     Every commuter train that departs from New York Cityabout 900 a d leaves a minute later than scheduled. If the timetable says 8:14, the train will actually leave at 8:15.In other words, if you think you have only a minute to get that trainwell, relax. You have two.     The courtesy minute , in place for decades and published only in private timetables for employees, is meant for those who need the extra time to get off the platform and onto the train.     "If everyone knows they get an extra minute, they're going to waste time doing unimportant things," explained Marjorie Anders, a spokeswoman for the Metro-North Railroad. Told of this article, Ms. Anders laughed. "Don't blow our cover!"she said.     Entirely hidden from the riding public, the secret minute is an odd departure from the railroad culture of down-to-the-second accuracy. The railroad industry helped invent the concept* of standard time, and time zones were established in the United States in the 1880s, 35 years before they were written into law. And most commuters know their train by the accurate minute it departs. The trains quickly make up the minute:at all other stops, the public timetable is carried out. The courtesy minute does not exist at commuter railroads in Chicago, Los Angeles, Philadelphia, or San Francisco. But in New York, the secret minute dates back decades.     "That's been done forever, from my knowledge," said Jack Swanberg, 70, an unofficial historian of Metro-North. "I was the trainmaster starting in 1970 and I'm sure it's been the case since 1870 for all I know." 
 Answer: prevent the passengers' idleness

The courtesy minute was hidden from the public to  _  .