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:
['2527', '9123', '8717']
answer:
-1


question:
['p', '4329', '2437', '6279', 'u', '459', 'f', 'c', 'i', 'w', 'n', 't', '429', 'n', '73', '4995', 'p', 'z', '8459', '6133', 'y', 'r', '4057', 'a', '2717', '7803', 'r', 'm', '2879', '6989', '7223', 'v', '7929']
answer:
a, c, f, i, m, n, p, r, t, u, v, w, y, z


question:
['z', '9683', 's', 'u', 'm', 'z', '9775', '7507', 'r', '309', 'n', '7345', 'l', 'a', 'm', 'r', '2687', 't', '7375', 'v', 'i', 'h', 'g', 'x', 'o', '2521', '5947', '8529', 'c', 'r', 'g', 'x', '3237', '6801', 's', 'c', '2297', 'w', '9209', 'y']
answer:

a, c, g, h, i, l, m, n, o, r, s, t, u, v, w, x, y, z