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: ['8495', 'p', 'j', 'm', 'n', '9115', '1183', 'r', 'r', '8735', 'a', 'i', 'k', 'p', '8927', 'r', '9283', '9563', 'g', '2503', 'h', '1091', '5257', 'a', '3061', '2835', 'l', 'w', 'j', '7617', '8793', '7463', 'h', '8467', '7337', 'b', '4655', 'd']

SOLUTION: a, b, d, g, h, i, j, k, l, m, n, p, r, w

PROBLEM: ['5433', '4011', '2113', '2299', 'e', '9829', 'd', 'q', 'e', '3921', 'a', 'q', '8953', 'q', 'g', 'w', 'z', 'u', '4425', 'b', 'q', '5315', 'b', 'u', 'h', 'y', '9733', 'b', 'c', '1225', 'a']

SOLUTION: a, b, c, d, e, g, h, q, u, w, y, z

PROBLEM: ['a', 't', '2229', 'j', 'f', '71', '5561', '6281', '371', '7371', '3925', 'v', '1103', '2831', 'f', '161', 'r', 'q', 'c', '7817', '9935', 'u', 'p', 'y', 'f', '6943', '7283', 'q']

SOLUTION:
a, c, f, j, p, q, r, t, u, v, y