The Plate Dispenser

The cafeteria dispenser: clean plates get pushed in on top, hungry kids take from the top. 🍽️

You get commands — add:blue pushes a blue plate, take removes the top one (there's always one to take). Print the final pile bottom to top, comma-separated, or empty.

Example:

Input: commands = ["add:blue", "add:red", "take", "add:green"] Output: blue,green

Push blue, push red, take removes red (the current top), then push green — leaving blue on the bottom and green on top: blue,green.