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.

Ex Input:
['7997', 'm']

Ex Output:
m


Ex Input:
['1063', 'f', 'm', 'i', 'x', 'i', 'd']

Ex Output:
d, f, i, m, x


Ex Input:
['r', 't', 'h', 'z', 'k', 'a', '401', '73', 'h', 'l', 'g', '2979', 'd', '6893', '5719', '2729', '7271', '5211', '3303', '8715', '7773', 'i', 'l', 'u', 'y', '7267', '6919', 'f', '7979', '8045', '6555', 'b', '5237', 's', '7715', 'g', 'k', '9379', '6279', '9331', '645', '5609', 'q']

Ex Output:

a, b, d, f, g, h, i, k, l, q, r, s, t, u, y, z