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: ['5163', 'n', 'j', '67', '3801', 'n', '7113', 'z', '579', '6885', '8921', 'v', '5481', '5507', 'k', '8403', 'c', '837', 'u', '6341', 'd', 'i', '497']

SOLUTION: c, d, i, j, k, n, u, v, z

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: ['6491', 'w', '7051', 'v', '7809', '1567', 'h', 't', '1411', 'l', 'x', '9677', '8367', 'v', '7293', '9977', '8709', 'q', '6067', 'k', '699', 'r', 'd', '71', 'd', 'f', '995']

SOLUTION:
d, f, h, k, l, q, r, t, v, w, x