Write a function that sorts a given array in an alternative fashion. The result should be a array sorted in ascending order (number then letter). Array will contain equal amounts of integer numbers and single characters.
alternateSort(["a", "b", "c", 1, 2, 3]) ➞ [1, "a", 2, "b", 3, "c"]
alternateSort([-2, "f", "A", 0, 100, "z"]) ➞ [-2, "A", 0, "f", 100, "z"]
alternateSort(["X", 15, 12, 18, "Y", "Z"]) ➞ [12, "X", 15, "Y", 18, "Z"]
N/A