During the next 12 months, the amounts of electric power needed (in thousands of kwh) are listed in the file P08_33.xlsx. This power can be supplied using four generators. The generating capacity (in thousands of kwh), the operating cost, the startup cost, and the shutdown cost (all costs in thousands of dollars) are also listed in the same file. At the beginning of month 1, generators 1 and 2 are in operation. At the end of each month, it is possible to either shut down an operating generator or start up a shutdown generator.