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.

['6769', '1057', '1021', 'n', '8231', '9173', '8123', 'a', '6053', 'q', 'y', '883', 'r', '1215', 'x', 'o', '9531']
a, n, o, q, r, x, y

['d', 'p', 'k', '9679', 'x', 'j', '7481', '1815', 't', 'w', '6513', 'j', '5079', '5219', 'p', '9545', 'a', '1931', '9973', '8125', '5169', '2791', 't', 'd', '2057', 'e', 'x', 'y', '7409', 'u']
a, d, e, j, k, p, t, u, w, x, y

['i', 'o', '5715', 'u', 't', 'g', 'e', '789', '9553', '4285', '7633', '3309', '5521', 'j', 'd', '8495', 'p', '909', '7147', '421', 't', 's', 'l', 'l', '5773', 'g', '5949', '4543', 'c', '7233', 'm', 't', 'd', '8289', 'b', '4327', '2217']

b, c, d, e, g, i, j, l, m, o, p, s, t, u