A manufacturer with exclusive rights to a sophisticated new industrial machine is planning to sell a limited number of the machines to both foreign and domestic firms. It is estimated that if the manufacturer supplies machines to the domestic market and machines to the foreign market, the machines will sell for −+ thousand dollars apiece domestically, and for +− thousand dollars apiece abroad. If the manufacturer can produce the machines at the cost of $ apiece, how many should be supplied to each market to generate the largest possible profit?