You are given an array of integers a, where each element a[i] represents the length of a ribbon.
Your goal is to obtain k ribbons of the same length, by cutting the ribbons into as many pieces as you want.
Your task is to calculate the maximum integer length L for which it is possible to obtain at least k ribbons of length L by cutting the given ones.
For a = [5, 2, 7, 4, 9] and k = 5, the output should be cutTheRibbons(a, k) = 4.
For a = [1, 2, 3, 4, 9] and k = 6, the output should be cutTheRibbons(a, k) = 2.