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:
['a', 'p', 'y', 'l', 'l']

Ex Output:
a, l, p, y


Ex Input:
['l', 'g', 'd', 'p', '8163', '6643', 'o', 'p', 'm']

Ex Output:
d, g, l, m, o, p


Ex Input:
['t', '4807', '4883', '57', 'z', 'r', 'x', 'h', 'z', 'm', 'p', 'a', 'c', '5655', '5075', '3839', '4333', 'e', 'r']

Ex Output:

a, c, e, h, m, p, r, t, x, z