One day, the head of the service department received a letter of complaint. "This is the second time I've written to you, but I don't blame you for not answering me last time, because even I think my complaint is absurd. Once again, I repeat the complaint as follows: Our family has a tradition of eating a little ice cream after dinner every day. When everyone votes on what kind of ice cream to eat, I drive to buy it. Not long ago, I purchased a Pontiac car made by your company. Within a few days, there was a problem: as long as I bought vanilla ice cream, the car would not start when I went back and forth from the store, but if I bought other kinds of ice cream, the car would start normally. I still don't understand this phenomenon, so although it sounds ridiculous, I decided to write this letter of complaint. "
What does it matter what kind of ice cream the driver buys when the car starts properly? The supervisor was incredible about such complaints, but he sent a technician to find out. When the technician met the complainer, he found that he was a well-educated person with high social status. To confirm the content of the complaint, the technician drove to the store to buy ice cream with the complaint after dinner that night. The complainer bought vanilla ice cream. Sure enough, back to the car, the car did not start.
However, the technician did not leave, and the next night he and the complainer drove again to buy ice cream. This time I bought chocolate ice cream. The car started normally. On the third night, I bought strawberry ice cream and the car started normally. On the fourth night, vanilla ice cream was bought, and the car could not start again.