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:
['8815', 'w', '8629', 'y', '3891']
answer:
w, y


question:
['8235', 't', '1695', '9899', '3633', 't', '1823', 'r', 'x']
answer:
r, t, x


question:
['q', '5265', 'z', 'a', '1783', '1437', '3877', 'o', '4143', '8407', '6473', 'm', 'n', 's', 'w', 'j', 'e', '1239', '4781', 'y', '2559', '4609', '483', '4951', '9921', 's', 'w', 'e', '8115', 'd', '1137']
answer:

a, d, e, j, m, n, o, q, s, w, y, z