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.

['6917', '1971', 'd', '3415', '7937', '8737', 'y', '9097', 'h', '1131', '3587', 'w', 'k', '625', 'y', '4803', '8899', 'w', 'h', '5841', '7315', 'i', 't', '3851', 'v', 'b', '3959', 'a', '6483', '8131', '9481', '4809', 'u', '1929', 'e', 'n', '8801', '8721', 'h', 'y', 'm', '6287', 'p', '5519', '1247']
a, b, d, e, h, i, k, m, n, p, t, u, v, w, y