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: ['9025', '3259', '4863', 'u', '6443', '9931', '627', 'x']

SOLUTION: u, x

PROBLEM: ['l', 'o', 's', '7411', '7847', '2557', '1977', '2863', '2325', '4177', '4183', '4241', '1005', '1137', '1371', 'v', 'p', 'a', '2453', 'l', '6315', 'l', '6463', 'n', '7645', '9669', '5411', '1631', '5995', 'z', '227']

SOLUTION: a, l, n, o, p, s, v, z

PROBLEM: ['t', 'v', '7711', 'm', 'q', '3861', 'y', '1661', '6955', 't', '4503', '9365', 'w', 'd', 'b', 'o', '5491', '325', 'd', 'r', 'r', '3915', '2157', '7575', 'i', 'a', 'n', '3935', '2565', 'b', '9957', '213', 'c', 'z', '429', '6261', '4955', '1737', '2831', 't', '6209']

SOLUTION:
a, b, c, d, i, m, n, o, q, r, t, v, w, y, z