Maximum Deliciousness

A new patisserie has opened up to rave reviews. You, in your quest for deliciousness, are going to visit it. The patisserie has $N$ pastries. With your trained eye, you judge that the $i$-th of them has *deliciousness* $A_i$. Of course, you want to eat pastries whose total deliciousness is as high as possible. Unfortunately, you can't just buy everything out. There are $K$ customers in the sto