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:
['m', '5005', 'y', 'h', 'w', '3609', 'p', '2539', '3307', 'p']
answer:
h, m, p, w, y


question:
['h', '6865', '4019', '8571', 'y', '5575', '7835', '9537', 'n', '875', 't', 'a', 's', '2769', 'p', '1607', 'n', '4087', '961', '7869', '5085', '2131', '4867', 'j', 'h', 'y', '3105', '6609', 's', 'l', '3399', '5013']
answer:
a, h, j, l, n, p, s, t, y


question:
['8705', 'e', 'g', '2769', 'r', '2737', '6187', 'j', '8951', '3409', 's', '9003', '1183', 'd', 'b', '5265', '9923', '5815', '1197', 'b']
answer:

b, d, e, g, j, r, s