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: ['9117', '1153', 'f', 'b', '9979']

SOLUTION: b, f

PROBLEM: ['t', 't', 'p', '3245', 'x', 'g', 'i', 'u', '2599', '8613', 't', 'v', 'p', '5635', 'y', '9567', '5193', '8617', 'q', 'f']

SOLUTION: f, g, i, p, q, t, u, v, x, y

PROBLEM: ['r', 'd', '1023', 'b', 'f', '8213', 'v', 'l', 'o', 'j', 'y', 'h', '2963', '5901', 'v', '373', 'm', 'v', '7819', '2619', 'b', '7365', '9373', '8149', '8681', '287', 'p', '875', '9755', '6269', '7225', 'h', 'o', '9511', '2159', 'n', '7059', '7169', 'o']

SOLUTION:
b, d, f, h, j, l, m, n, o, p, r, v, y