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: ['4857', 'z', '313', '7813', '9935', 'o', 'w', 'i', 'x', 'o', 'e', 's', 'a', 'p', 'i', 'v', 'x', '6743', 'p', '435', 'u', 'a', 'h', '607', '2491', '6159', 'u', '7761', '6197', '3449', '3459', 'e', 'g', '8731', '335', '2883', '3941', 'n', '1881', 'y', 'j', '8189', 'k', '7593', '2747']

SOLUTION: a, e, g, h, i, j, k, n, o, p, s, u, v, w, x, y, z

PROBLEM: ['4743', '9687', '2887', '4413', 'r', 'w', '2355', 'l', 'd', '453', 'o', 'm', '4351', '5881', '3963', 'g', 'r', 'z', 'q', '7555', 'y', '9555', '405', 'n', 'l', '6733', '1763', 'v', '9925', 'y', '633', '827', 'w']

SOLUTION: d, g, l, m, n, o, q, r, v, w, y, z

PROBLEM: ['4907', 't', '1709', 'j', '7293', '7443', '1935', 'q', 'b', 'u', '2255', 'g', 'p', 'h', '7513', 'a', '2159', 'f', 'l', '57', 'g', 'q', 'l', 'q', 'i', '7047', '9475', 'h', 'r', 'o', '8353', 'z', '3601', 'd', '551', 'p', '199', '7997']

SOLUTION:
a, b, d, f, g, h, i, j, l, o, p, q, r, t, u, z