“1. A man decided to rob 2. a bank in the town where he lived. He walked into 3. the bank and handed 4. the note to one of 5. the cashiers. 6. The cashier read 7. the note, which told her to give 8. the man some money. Afraid that he might have 9. a gun, she did as she was told. 10. The man then walked out of 11. the building, leaving 12. the note behind. However, he had no time to spend 13.the money because he was arrested 14. the same day. He had made 15. a mistake. He had written 16. the note on 17. the back of 18. an envelope. And on 19. the other side of 20. the envelope was his name and address. This clue was quite enough for 21. the detectives on the case.”