Package Rice Bags (part 2)

Provided that you have a given number of small rice bags (1 kilo each) and big rice bags (5 kilo each), write a method that returns the minimum number of small bags necessary to package goal kilos of rice. Return -1 if it is not possible to package the required rice amount with the bags provided.

public Integer getNumberSmallBags(Integer big, Integer small, Integer goal) {