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:
['t', 'h', '6141', 'g', 'f', 'z', 'n', 'b', 'k', '9059', 'y', 'p', '4289', '2683', 'a', '3267', 'w', 'p', 't', '3623', '7759', 'a', 'o', 'm', '9815', 'q', 'u', '8051', '6871']
answer:
a, b, f, g, h, k, m, n, o, p, q, t, u, w, y, z


question:
['i', '1129', 'f']
answer:
f, i


question:
['4171', 'y', 'j', '2029', 'e', 'c', 'v', 'x', '8595', '8013', '5437', 'd', '7667', '4411', 'r', 'z', 'f', 'd', '9057', 'g', 't', 'b']
answer:

b, c, d, e, f, g, j, r, t, v, x, y, z