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: ['3821', '385', 'y', '8457', '6623', 'g', '5923', 'a', '7193', 'v', 'm', '8915', 'v', '5873', 'p', 't', 'w', 'y', '3617', 'h', 'w', 'j', '8047', 'u', '2271', 'v', 'a', '2181', 's', '1051', 'b', 'a', '9967', '987', 'z', '2255', '6349', '1249', '1397', 'q']

SOLUTION: a, b, g, h, j, m, p, q, s, t, u, v, w, y, z

PROBLEM: ['w', 'l', 'f', 'i', 'x', 't', 'b', '2151', '2985', '817', 'j', 'b']

SOLUTION:
b, f, i, j, l, t, w, x