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: ['d', '2359', '6571', 'c', 'n', 'u', '9513', '9321', '1689', 'b', '969', '1823', 'e', 'b', '9147', 's', '1811', 'k', '5443', '8699', '5483', 'v', 'w', 'n', '1215']

SOLUTION: b, c, d, e, k, n, s, u, v, w

PROBLEM: ['r', 'j', '437', 'b', '5223', 'n', 'v', '437', 'd', '8285', 'k', 'j', 'r', 'p', 'n', 'e', 'n', 'j', 'o', '2651', 'j', '6365', 'q', 'q', '2159', 'g', '3641', '7727', 'c', '1197', 's', 't', 'n']

SOLUTION: b, c, d, e, g, j, k, n, o, p, q, r, s, t, v

PROBLEM: ['5649', '5333', 'm', '8443', '4401', '4343', '9259', 't', 'c', 'u', '5565', '4933', '4915', '3271', 'o', '2099', '1917', 'o', 'm', '8891', 'd', 'e', 'v', '2493', '1473', 's', '8525', 'b', 'o', '2261', 'v', 'o', 'z', '1129', 'g', 'h', '6341', '9949', '2779', 'e', '9593']

SOLUTION:
b, c, d, e, g, h, m, o, s, t, u, v, z