|A prefix-free code of size N which uses K characters is a set of N distinct strings such that
You are given the size of the code N and the costs of using the characters characterCosts. Return the minimal possible cost of a prefix-free code of size N which uses these character costs.
|-||N will be between 2 and 500, inclusive.|
|-||characterCosts will contain between 2 and 50 elements, inclusive.|
|-||Each element of characterCosts will be between 1 and 100, inclusive.|