You have an electric car that you want to use to transport some batteries 1,000 miles. You have 3,000 batteries, but your car can only carry 1,000 of them at once. In addition, for each mile that it travels, the car will need to use up one battery in order to power itself.
How many unspent batteries will you be able to transfer to your destination?
Is transporting all the batteries a requirement, or just as many unspent batteries as possible?