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: ['4749', '4607', '625', '6907', 't', 'b', '8479', '6505', 'r']

SOLUTION: b, r, t

PROBLEM: ['1593', '8165', 'q', '6689', 'b', 'r', '373', 'g', '6505', '415', '495', 'j', 'j', 'f']

SOLUTION: b, f, g, j, q, r

PROBLEM: ['q', 'b', 'o', '4861', 'x', 'q', 'c', '4429', 'q', 'f', '7447', 'm', '2185', 'r', 'g', 'z', '179', 'i', '4275', 'b', 'n', 'n', 's', '1211', 'g', 'f', 'b', 'h', 'v', 'h', '7677', '3485', '779', '3263', 'i', 'i', 'u', '5483', '8417', 'g', 't']

SOLUTION:
b, c, f, g, h, i, m, n, o, q, r, s, t, u, v, x, z