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: ['w', '6291', '3939', '9569', 'u', '1635', '3359', '8335', 'n', '2799', '7359', 'k', 'm', '2817']

SOLUTION: k, m, n, u, w

PROBLEM: ['789', '3603', '3517', '5831', 'z', 'q', 'w', 'l', '5701', '9503', '8169', '1123', 'e', '529', 'j', 'z', 'l', 'o', '3705', 'o', '5131', '6063', 'c', 'j', '6275', '7701']

SOLUTION: c, e, j, l, o, q, w, z

PROBLEM: ['8227', '9091', '6517', 'q', '5257', 'c', 'e', '3705', '5313', 'k', '6543', 't', 'b', 'e', '5739', '4033', 'k', '8227', 'r', 'm', 'j', 'b', '9413', 'i', 'm', 'g', 'n', 'q', 't', 'o', 'r', '6625', 'q', '8049', '1421', 'q', 'r', '5611', '1875', '7261', '2333', 'n', 'q', '6075']

SOLUTION:
b, c, e, g, i, j, k, m, n, o, q, r, t