The demand forecast for the next four periods is 80, 110, 120, and 145 units respectively. The plant has a regular capacity of 100 units per period, an overtime capacity of 10 units per period, and a subcontractor capacity of 5 units per period. Costs per unit are: Regular production: $5 Overtime production: $8 Subcontracting: $9 Holding cost per unit per period: $3 No shortages are allowed and the company has 5 units in inventory at the start of the planning period. How many units should be produced using overtime?