Quantity of Gold Bars (in thousands)	Extraction Cost (in millions of dollars)	User Cost (in millions of dollars)
0	$ 10	$ 10
1	15	10
2	20	10
3	25	10
4	30	10
5	35	10

The table shows the quantity of gold bars in thousands, the extraction cost for each thousand bars (in millions of dollars), and the user cost of each thousand bars (in millions of dollars) facing the OZ Mining Company this year (all costs are marginal). If the current price of a bar of gold is $35,000, how many bars (in thousands) should OZ extract and sell this year in order to maximize profits?