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: ['l', '6313', '3199', 'w', '249', '8747', '7391', '3871', '173', 'x', 'o', '8647', '4413', '3645', '6123', '701', 'q', '2147', '4289', '7333', '533']

SOLUTION: l, o, q, w, x

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: ['j', '4869', 'f', 'm', 'x', '3003', '1819', '3445', '8787', '9067', '2779', 'k', '3739', '1447', '627', '2875', 'w', 'k', 'k', 'q']

SOLUTION:
f, j, k, m, q, w, x