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: ['8489', 'h']

SOLUTION: h

PROBLEM: ['4371', '9499', 'e', 'w', '9969', '8367', '2897', '1745', 'i', '7049', '9773', 'h', '9649', 'u', '4673', '8513', '8547', 'z', '1995', '7739', '2215', '171', 'c', '7527', '2479', 't', '5223', 'p', '2313', '3243', '2281', 'r', 'c']

SOLUTION: c, e, h, i, p, r, t, u, w, z

PROBLEM: ['l', 's', 'f', '373', 'n', 'n', 'w', 'n', 'w', '7705', 'r', '7015', 'j', 'u', '7681', 't', 'j', '2447', 'g', 'u']

SOLUTION:
f, g, j, l, n, r, s, t, u, w