There is a three$-$plate stack in a canteen with a spring inside. The plate placed first stays at the top

because of the spring. The two bottom places are empty. When a second plate is placed on the top, the

previous plate moves to the middle place. When a third plate is placed on the top, the previous $($second

plate$)$ goes to the middle place and the first plate goes to the bottom of the stack. There is only one

place in the stack from where a plate can be placed $($Inserted$)$ in it or can be removed $($deleted$)$ from it

and that is the top of the stack. This is essentially a LIFO $($Last In First Out$)$ system.