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: ['g', 'u', 'q', '1375', '9491', 't', 'w', 'c', 'v', 'y', '3169', '1607']

SOLUTION: c, g, q, t, u, v, w, y

PROBLEM: ['8051', 'h', 'g', 's', 't', 'p', 'w', 'x', 's', '8521', 'm', '9719', 'j', 'n', 'i']

SOLUTION: g, h, i, j, m, n, p, s, t, w, x

PROBLEM: ['v', '7975', '8785', '9295', '4975', '2795', '2801', 'h', '6281', '743', '8011', 'n', 'd', 't', 'x', 's', 'b', '9159', '2785', '5979', '9447', '6115', 'y', 'y', '9073', 'e', '8005']

SOLUTION:
b, d, e, h, n, s, t, v, x, y