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.

['y', 'g', '107', '4899', '6357', '9777', 'k', '1865', '7029', 'q', 'x', '7051', 's', '6125', '4285', '2731', 'z', 'a', '737', '6137']
a, g, k, q, s, x, y, z

['e', 'c', '4241', '2685', 'o', '9859', 'z', '2647', 'b', 'c', 'y', '1985', '5985', '5709', '6655', 'q', 'z', '9933', '6817', '6477', '1837', 'x', 'p', '9251', '3787', 'v', '5741', 'e', 'p', '493', '5949', '5519', 'v', 'g', '1403', 'z', 'h', 'z']
b, c, e, g, h, o, p, q, v, x, y, z

['9209', 'x', '4937', 's', 'v', '9643', '3257', '8311', 'b', '8159', '4999', 'q', 'h', '5075', 'q', 'o', '5567', 'k', '1991', '8669', 'r', '7145', 's', 'm', '815', '9391', '7267', 'o', 'o', '5547', 'q', '1625', '5575', 's', 'f']

b, f, h, k, m, o, q, r, s, v, x