Consider a function, f$($ L$[$n$]),$ that takes in a list of integers, L$[$n$],$ and returns an integer value. Let n be the length of the list. f$($ L$[$n$])$ is O$($k$)$ regardless of the length of the list. f$($ L$[$n$])$ is a black box function, meaning we can't determine ahead of time what the output will be for any input. In addition, the order of the integers in L$[$n$]$ does not affect the output of f$($ L$[$n$]).$

Problem, P$,$ is defined as follows: Given a list of integers, L$[$n$],$ find the subset of integers, L$\text{'},$ such that f $($L$\text{'})$ returns the maximum value.

What is the complexity of P$?$ If P is undecidable, state that and justify your answer.