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.

['u', '4731', 'l', 'p', '1997', '601', 'n', 'l', 'p', '211', '7355', '6537', 'w', 'x', '1741', '8145', '3689', 'm', 'y', '6945']
l, m, n, p, u, w, x, y

['g', 'h', 'g', 'g', 's', 'h', '2849', '2705', '1185', 'x', '5789', '8221', 'e', 'x', 'g', 'b', '4903', 'q', '1563', 'r', 'k', 't', '9047', 'p', 'p', '9397', 'u', '7473', 'f', 'o', 'y', '1957', '1039', '9905', 'i', '4829', 'q', 'w', 'k', 'p', 't', '563', 'g', 'l']
b, e, f, g, h, i, k, l, o, p, q, r, s, t, u, w, x, y

['3297', '4555', 'z', 'f', 'g', 'i', '4239', 'v', 'o', 'q', 'o', '1411', '4809', 'a', 'z', '1029', '5723', 'q', '4355', '5297', 's', '7327', 'p']

a, f, g, i, o, p, q, s, v, z