Up, Up, and Away is a producer of kites and wind socks. Relevant data on the bottleneck operation in the shop for the upcoming fiscal year are given in the following table: Item Kites Wind Socks Demand forecast 30,000 units/year 15,000 units/year Lot size 15 units 80 units Standard processing time 0.2 hour/unit 1.0 hour/unit Standard setup time 3.0 hours/lot 4.0 hours/lot The shop works two shifts per day, 8 hours per shift, 220 days per year. Currently, the company operates four machines, and desires a 25 percent capacity cushion. How many machines should be purchased to meet the upcoming year's demand without resorting to any short-term capacity solutions? The number of additional machines required is (Enter your response rounded up to the next whole number.)