solve with gams, please provided the code for the gams

Carco uses robots to manufacture cars. The following demands for cars must be met (not necessarily on time, but

all demands must be met by end of quarter 4): quarter 1 600; quarter 2800; quarter 3500; quarter 4400. At

the beginning of the quarter, Carco has two robots. Robots can be purchased at the beginning of each quarter, but a maximum of two per quarter can be purchased. Each robot can build as many as 200 cars per quarter. It costs $5,000

to purchase a robot. Each quarter, a robot incurs $500 in maintenance costs (even if it is not used to build any cars). Robots can also be sold at the beginning of each quarter for $3,000. At the end of each quarter, a holding cost of $200

per car is incurred. If any demand is backlogged, then a cost of $300 per car is incurred for each quarter the demand is backlogged. At the end of quarter 4, Carco must have at least two robots. Formulate an LP to minimize the total cost incurred in meeting the next four quarters demands for cars.