instruction:
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.
question:
['i', '4447', 'g', 'o', 'j', 'p', 'l', 'q', 'o', '8777', 'r', 'v', '961', '6083']
answer:
g, i, j, l, o, p, q, r, v


question:
['w', '8777', 'y', 'e', '8015', 't', 'w', '53', '9149', 'e', 'k', '1837', 'b', 's', '4007', '4905']
answer:
b, e, k, s, t, w, y


question:
['6289', 'l', '7589', '6331', 'y', '9155', 'o', 'n', 'm', '2653', '67', '87', 'x', '3733', '9733', '1625', 'c', 'q', 'k', 'o', 'o', 't', 'j', '7471', '6231', '7439', 'n', '3797', 't', 'd', '4513', '8379', 'p', '9909', 't', 's', '1441', '8683', '6105', 'g', 'a']
answer:

a, c, d, g, j, k, l, m, n, o, p, q, s, t, x, y