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: ['9689', '9727', 't', 'd', '2103', 'c', 'n', '8553', '4559', '7815', 'u', 'l', 'c', 'e', 'u', 'n', '7207', '4875', '7699', 'h']

SOLUTION: c, d, e, h, l, n, t, u

PROBLEM: ['2705', 'n', 'r', '8259', '6839', '3239', 'w', 'z', '2611', '2957', '2303', '6315', '7801', 'c', 'w', 'm', '5049', '6465', '599', 'h', 'q', '7559', 'n', '9917', 'v', 'l', '643', '6415', '3587', 'c', '917', '4435', 'p', 'a', '317']

SOLUTION: a, c, h, l, m, n, p, q, r, v, w, z

PROBLEM: ['t', 'j', '8205', '6149', 'h', 'v', 'p', '5497', 'q', 'n', 'z', '6817', 'l', 'i', 'v', 'v', '8143', '3841', 'g', 'h', '217', 's', '3921', '1063', '1863', 'h', '5191', '3503', 'j', '9407', 'a', '4207', '4021', 'o', '4093', 'n', 'n']

SOLUTION:
a, g, h, i, j, l, n, o, p, q, s, t, v, z