In this task, you are given an input list A comprising of numbers and alphabets. You need to extract and sort the unique alphabets in the list. The alphabets in the input list will only be in lowercase. Return -1 if there is no alphabet in the input list.

Input: Consider Input: ['3147', '9807', '5313', '6311', '737', '1555', '5803', '3437', '5665', '3973', 'o', 'f', '7871', '1721', '7833', '2933', 'b', 'b', 'n', 'm', 'k']

Output: b, f, k, m, n, o


Input: Consider Input: ['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']

Output: j, m


Input: Consider Input: ['e', 'p', '7783', '6915', 'b', '9519', 'd', 'f', '6231', 't', '3787', '3981', 'v', '7645', '6777', 'm', '8447', '9939']


Output: b, d, e, f, m, p, t, v