There is a room full of vending machines . I had a 20 dollar bill and I wanted a Coke Zero . In a quiet hour , I walked down to the emergency department and asked the clerk if there was a cashier anywhere who took payments at night , so I could get change . He sent me to the security desk , staffed by a VA police officer who told me that there was no cashier anywhere , and no change machine he could think of .
According to the above context, answer the following question.
Why did the narrator need to get change ?


They wanted to buy themselves a snack .