Production planning

A firm is planning the production of 3 products A1, A2, A3 over a time horizon of 
4 months (january to april). Demand for the products over the months is as follows:

                             Demand      January    February   March   April
                                 A1       5300        1200      7400    5300
                                 A2       4500        5400      6500    7200
                                 A3       4400        6700     12500   13200

Prices, production costs, production quotas, activation costs and minimum batches are:

                                  Product           A1        A2         A3
                                Unit prices        $124      $109       $115
                             Activation costs    $150000   $150000     $100000
                             Production costs     $73.30    $52.90     $65.40
                            Production quotas       500       450        550
                             Minimum batches         20        20        16

There are 23 productive days in january, 20 in february, 23 in march and 22 in april. 
The activation status of a production line can be changed every month. Minimum batches are
monthly.
Moreover, storage space can be rented at monthly rates of $3.50 for A1, $4.00 for A2 and $3.00 for
A3. Each product takes the same amount of storage space. The total available volume is 800 units.

Write a mathematical program to maximize the profit, and solve it with AMPL.