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: ['h', 'b', '9601', 'h', 'h', 'h', '8099', '8265', 'i', 'd', '8791', 'p', '8059', '4309', '501', '2581', '9837', '157', '4785', '5925', 'q', '8491', '4779', 'r', 'l', 'k', '3679', 'v', 'g', 'g', '9731', '1909', '9783', 'f', '4293', '5009', 'o', '3057', '3157', 'c', '5587', 'b', 'f', 'd', 'k']

SOLUTION: b, c, d, f, g, h, i, k, l, o, p, q, r, v

PROBLEM: ['g', '8591', '4463', '2189', '7901', '1457', 'f', 'i', '9031', 'r', '5519', '3955', 'd', '2093', 'c', 'y', '6591', '6463', 'h', '4371', '111', 'p', '3221', '4185', 'p', '8761', 'w', 'p']

SOLUTION: c, d, f, g, h, i, p, r, w, y

PROBLEM: ['521', '1243', 'c', 'p', 'w', 'i', '3403', '1657', '4289', 'n', 'm', '4453', '2225', 't', 'o', 'c', 'x', '1883', '3401', '37', '8311', '6393', 'c']

SOLUTION:
c, i, m, n, o, p, t, w, x