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: ['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: ['9783', '3185', '8225', 'u', '1123', 'd', '3453', 'i', '7713', '8457', '8609', 'h', '2767', 'e', '7191', '2929', '1089', '393', 'e', 'd', '11', '9329', '683', '1271']

SOLUTION: d, e, h, i, u

PROBLEM: ['j', '4395', '7529', 'h', '929', '4239', '6281', 'u', '1383', 'n', 'u', '591', 't']

SOLUTION:
h, j, n, t, u