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.

['z', '8407', 'y', 'h', '1377', '3511', '1449', 'z', '3991', 'n', 'x', 't', 'h', '6389', '8049', '6091', '7787', 'p', 'l', '5815', 'k', 'e', 's', 'a', '9491', 'w', '1909', '4801', '4725', 'i']
a, e, h, i, k, l, n, p, s, t, w, x, y, z

['4371', '9499', 'e', 'w', '9969', '8367', '2897', '1745', 'i', '7049', '9773', 'h', '9649', 'u', '4673', '8513', '8547', 'z', '1995', '7739', '2215', '171', 'c', '7527', '2479', 't', '5223', 'p', '2313', '3243', '2281', 'r', 'c']
c, e, h, i, p, r, t, u, w, z

['4031', 'a', '7647', '1365']

a