TASK DEFINITION: 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.
PROBLEM: ['6181', 'w', '4663', '5507', 'a', '6607', '869', '2669', 'r', '3629', 'r', 'l', '6599', '8885', 's', '4315', 'z', 'l', 'r', '1225', '8371', '1545', '7169', '1175', 'k', 'p', 'y', '7263', '5537', '8649', '3317', 'q', 'r', 'u', 'd', '4647', 'u', 'y', 'h', '9753', 'q', '725']

SOLUTION: a, d, h, k, l, p, q, r, s, u, w, y, z

PROBLEM: ['z', '5601', '5675', 'w', 's', 'z', '9213', '9563', '1699', 'p', 'g', 'm', 'c', '9279', '4481', 'p', 'n', '2389', 'c', '503', '1901', '8827', '1701', '1607', '5633', 'a', 'z', 'g', '3175', 's', 'l', 'l', '6811', '1821', '693', '8277', 'q', '8623', 'o']

SOLUTION: a, c, g, l, m, n, o, p, q, s, w, z

PROBLEM: ['w', 'f', 'n', 'j', 'q', 'e', '4879', '9419', 'y', '5259', '5581', 'c', '2705', 'l', '31', '6011', '4003', 't', 'q', '9091', '6757', 'o', '5409', '4171', 'd', 'v', '8445', '775', 's', '6529', '8895', '3447', 's', 'z', '9745', '4113', 'k', 'r', '2229', 's', '2995', '1393', 'i', 'l']

SOLUTION:
c, d, e, f, i, j, k, l, n, o, q, r, s, t, v, w, y, z