Simulator of Vending Machine

This is a simulator of a vending machine.
By increasing or decreasing setting and the amount the input button of the quantity of goods,
it will enable merchandise purchase.

1. Quantity increase and decrease button
Numerical commodity display color will be from yellow to black with one or more.
2. Payment button
If the payment is greater than the price of the commodity goods display color will be red.
3. Commodity purchase button
Change the balance by pressing the purchase button.
4. Charge button
Charge is displayed by pressing the Charge button.