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', '4021', 'u', 'd', 'j', 'p', 'i', 'z', '3223', 'f', 's', 'l', 'p', 'd', '5031', '1059', '7875', '2097', 'q', 'i', '8813', '2017', 'h', 'l', 'y', '57', '1561', 'f', 'j', 'z', '1901', 'u', 'j', 'x', '6561', '9239', '3333', '8793', '4915', '5821', 'h', 'f', '765', 'x']

SOLUTION: d, f, h, i, j, l, p, q, s, u, x, y, z

PROBLEM: ['i', 'i', 'h', 'g', '5123', 'i', 'r', '3183', 'w', 'g', 's', '9777', '455', 'l', 'r', 'h', 'e', 's', 'v', '6823', '463', '9603', 'e', '947', '7071', 'c', '3373', 'j', 'w', 'm', 's', 's', '3483', '9567']

SOLUTION: c, e, g, h, i, j, l, m, r, s, v, w

PROBLEM: ['1421', 'f', '6023', 's', '9699', 'l', 'c', '3943', '2311']

SOLUTION:
c, f, l, s