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.

['7911', '7175', 'y', '9173', 'y', '2529', '831', 'k', '7197', 'j', '2343', 'i', 'b', '6799', '5987', '7277', 'n', 'x', 'h', '7209', 'l', 'd', 'm', 'e', '2277', '8909', 'x', '5361']
b, d, e, h, i, j, k, l, m, n, x, y

['7155', 'y', '145', '7147', 'u', '8453', 'd', '3693', '6471', '5289', 'n', 'p', '8289', '2929', '199', 'e', '8377', '8937', '5315', 't', 'l', '7715', 'c', 'y', 'f', '9999', 'p', '3655', '5489', 'q', '2321', '9881', '2265', 'n', 'v', '455']
c, d, e, f, l, n, p, q, t, u, v, y

['j', 'x', '8903', '4609', '957', '7479', '3413', 'z', 'm', 'n', '7489', 'h', 'c', '1709', '6981']

c, h, j, m, n, x, z