Vaccine Distribution

Finally, a COVID vaccine is out on the market and the Chefland government has asked you to form a plan to distribute it to the public as soon as possible. There are a total of $N$ people with ages $a_1, a_2, \ldots, a_N$. There is only one hospital where vaccination is done and it is only possible to vaccinate up to $D$ people per day. Anyone whose age is $\ge 80$ or $\le 9$ is considered to be