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:
['9425', 'l', 'c', 'n', '5925', '2543', '3935', 'c', '7533', 'j', 'q', '3775', '5897', '9435', '69', 'e']
answer:
c, e, j, l, n, q


question:
['6599', 'f', 'c', '661', 'q', 'e', '1951', 'f', 'f', 'a', 'd', '9521', '853', 'n', 'w', '6451', '5549', 'k', 't', 'l', 'z', 'm', 'k', '567']
answer:
a, c, d, e, f, k, l, m, n, q, t, w, z


question:
['8523', '8423', '1829', '1331', 'd', '441', '7051', 'c', '8745', 'w', 'f', '1535', '921', 'f', 'p', 'd', '1213', 'j', '729', 'c', 'd', 'm', 'a']
answer:

a, c, d, f, j, m, p, w