A small computer manufacturing company forecasts the demand over the next n months to be di i = 1 2n. In any month it can produce r units, using regular production, at a cost of b dollars per unit. By using overtime, it can produce additional units at c dollars per unit, where c>b. The firm can store units from month to month at a cost of s dollars per unit per month. Formulate the problem of determining the production schedule that minimizes cost.