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: ['8887', '1199', 'r', '7209', 'k', '7567', '7239', 'k', '5123', 'w', '4523', 't', 'd', '5289', '5737', '485', 'w', 't', '7651', 'v', '7213', '7687', 'y', 'w', '7265', 'b', 'b', '3667', 'z', '9935', 'i', 'l', 'u', '6715', 'j', '9815', '8925', '7941', 'w', 'm', '3907', '621', '5523', '5849']

SOLUTION: b, d, i, j, k, l, m, r, t, u, v, w, y, z

PROBLEM: ['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']

SOLUTION: j, m

PROBLEM: ['303', 'z', 'a', 'n', '4957', '6951', '6907', 'q', '5371', 'i', 'i', '5987', 'h', '5025', '2049', '3811', '6255', 'l', 'o', '2689', '5817', 'r', 'z', 'r', 't', 't', '6955', 'k', 'w', '155', 'n', 'k', '2877', 'q', '8161', '4145']

SOLUTION:
a, h, i, k, l, n, o, q, r, t, w, z