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: ['u', 'i', '1185', '3795', '5417', 'k', 'b', '2629', '2635', 'z']

SOLUTION: b, i, k, u, z

PROBLEM: ['x', '4283', 'n', 'b', 'g', 'p', '8305', '7781', '5907', 's', '1305', 'w', '8623', 'o', 'c', 'u', '1839', '2869', '7537', 'y', '2395', '5309', 'e', '4059', 'l', '6647', 'p', '9717', 'y', 'y', '3769', '2527', '2981', '5255', '4063', 'j', '4843', 'j', '9355', 'z']

SOLUTION: b, c, e, g, j, l, n, o, p, s, u, w, x, y, z

PROBLEM: ['t', '1761', '5431', '5545', '2825', '945', '5021', '3533', '1161', '9513', '6467', '5263', 'b', '6717', '4277', 'o', '491', '7565', '6311', 'r', '6767', 'a', '4571', 'm', 'j', 'r', 'x', 't']

SOLUTION:
a, b, j, m, o, r, t, x