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: ['m', '6443', 'd', 'o', 'p', 'q', '3765', 'k', 'm', 'y', 'j', '3531', 'y', 't', '671', 'j', '3699', 'a', 'i', '1843', 't', 'd', '1205', 'k', 'h', '1209', '2913', '1301', 'k', 'd', '1769', '7985', 's', 'p', 'f', '4583']

SOLUTION: a, d, f, h, i, j, k, m, o, p, q, s, t, y

PROBLEM: ['4423', '8295', 'h', '4881', 'j', 'c', '1185', 'z', 'm', '2725', 'p', '9187', '6275', '1617', '2523', '9879', '4149', '2197', '3909', '5155', '691', 'r', 'e', 'u', 'l', 'd', '1581', '2763', 'c']

SOLUTION: c, d, e, h, j, l, m, p, r, u, z

PROBLEM: ['6601', 'k', 'y', '3921', 'i', '9715', '8081', 'm', '9177', '9753', '5085', '3485', '6133', 'c', 'c', 'q', '227', 'c', 'e', '6155', '7769', '8253', 't', '2493', 'r', 'l', 'g', '7409', '4925', 'h', 't', '4165', 'l', '1115', 'u', '4083', '673', 'a', '1575', 'x', 'v', 't', 'i', 'n']

SOLUTION:
a, c, e, g, h, i, k, l, m, n, q, r, t, u, v, x, y