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: ['e', 'k', '7569', '6387', '4593', '2445', '345', '2905', 'h', '3119', '7001', 'x', 'a', '2943', '3635', 'l', 'q', 'z', 'g', '2657', '7849', 'i', '9413', 'm', 'e', '2951', 'd', '2963', 'b', 'u', 't', 'i', '1141', 'c', 'm', '8607', 's']

SOLUTION: a, b, c, d, e, g, h, i, k, l, m, q, s, t, u, x, z

PROBLEM: ['j', 'p', '8333', '8079', '4703', '7089', '8859', 'b', 'y', 'g', '7971', '6999', '2011', 'k', 'e', '9609', '4179', '3993', 'u', '3957', '6313', '4229', 'k', '5963', 'e', 'y', 'r', 'e', 'a', '2213', 'e', 'i', 'f', '7979', 'r', 'a', 'h', 'e', 'n']

SOLUTION: a, b, e, f, g, h, i, j, k, n, p, r, u, y

PROBLEM: ['4073', '7155', 'z', '7973', '4641', 'q', '381', '5749', 'k', '1439', 'n', '599', 'c', '3889', '5205', 'x', '5781', 'm']

SOLUTION:
c, k, m, n, q, x, z