A chemical plant can buy two types of generators, generator A and generator B, which use two different processes to generate hydrogen. Generator A uses an electrolysis process and produces 40 cubic meters of hydrogen as well as 300 units of pollutants every day. Generator B uses a fermentation process to produce 30 cubic meters of hydrogen per day while outputting 200 units of pollutants. The chemical plant must make a minimum of 1000 cubic meters of hydrogen per day but due to environmental restrictions they can produce at most 3000 units of pollutant. How many of each type of generator should they buy to minimize the number of generators needed?