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: ['5957', 'd', 'i', 'b', 'e', '5565', 'c', 'i', '2919']

SOLUTION: b, c, d, e, i

PROBLEM: ['4637', 'f', '2639', '8623', 'w', 'e', 'k', '5503', 'x', '6633', '7553', '1455', 'u', '1773', 'r', 'u', '1489', 'u', '1303', '9683', 'z', '565', '7041', 'x', 'z', '9431', 'k', 'v', 'j', 'z', '5469', '5665', '4089', '4951', '8263', '5675', '4095', '7745', 'z', '2437', 'd', 'e', 'w']

SOLUTION: d, e, f, j, k, r, u, v, w, x, z

PROBLEM: ['b', '8031', 'u', 'k', '5409', 'i', 'q', '3377', 'g', 's', '2823', 'g', '9923', '5309', 'a', '8935', '2173', 'f', 'u', 'e', '4925', 'm', '4623', 'x', 'z', 'y', '4919', '8787', '7267', '2195']

SOLUTION:
a, b, e, f, g, i, k, m, q, s, u, x, y, z