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.

['4749', '4607', '625', '6907', 't', 'b', '8479', '6505', 'r']
b, r, t

['w', '1349', '3393', '7507', '2469', '8531', 'w', '6845', 'k', 'q', '2401', 'f', 'g', 'l', 'n', 'n', 'e', 'q', 'y', 'v', '3077', '4167', 'b', '5517', 'b']
b, e, f, g, k, l, n, q, v, w, y

['7263', 'b', '69']

b