actory forecasts the demand for its product over the next n months to be d$1,...,$ dn$.$ In any month,factory forecasts the demand for its product over the next n months to be d$1,...,$ dn$.$ In any month, the factory has a regular production capacity of r units, at a cost of b dollars per unit. If it goes into overtime production, then it can produce additional units at a cost of c dollars per unit, where c $>$ b$.$