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: ['w', 'g', '1649', 'a', '2115', '6763', 'r', 't', 'l', 's', 'y', '5659', 'a', 'b']

SOLUTION: a, b, g, l, r, s, t, w, y

PROBLEM: ['3659', 'i', '3383', '1023', 'j', 'q', 'm', 'i', 'i', 'e', '2427', '1647', 'y', '3789', '2683', 'p', '3119', 'z', 'x', 'r', '333', '3745', 't']

SOLUTION:
e, i, j, m, p, q, r, t, x, y, z