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:
['6175', '9441', '7127', '5979', 's', '1367', 'e', 'm', '7083', '1787', '8375', '2851', '3475', 'r', '697', 'g', 'z', 'm', '4207', 'c', '7971', 'z', '9339', 'd', 's', '3507', '9003', 'i', 'y', 'w', 'j', 'i']
answer:
c, d, e, g, i, j, m, r, s, w, y, z


question:
['6027', 'v', 'b', 'l', '7853', 'r', 'y', '2919', '3831']
answer:
b, l, r, v, y


question:
['93', 'p', 'k', '8853', '475', 'n', 'f', 'j', '1075', '8019', 'p', '299', '1023', 'd', '849', '1817', '2485', '7799', '173', '8227', 'a', 'k', '8245', '5061', 'l', '9551', 's', 'm', '189', 'h', '4293', '3085', '3875']
answer:

a, d, f, h, j, k, l, m, n, p, s