The game develops a quick score in the mind with negative and positive numbers.
In the game you need to collect the sum of the numbers, which is indicated on the right of the screen. The amount on the left is shown on the screen, which is already collected. If you want to collect a negative number, do not let your sum (on the left) reach zero. If you want to collect a positive number, do not let your sum (on the left) reach -1