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', 'g', 'j', 'i', 'y', '7799', 'y', 'e', 'y', 'e', '6757', '3349', '1213', '191', 'd', '2149', '849', '8325', 'b', '6087', 'w', '7211', '7801']

SOLUTION: b, d, e, g, h, i, j, w, y

PROBLEM: ['1931', 'c', 's', '8767', 'z', '8977', '9249', '365', 'p', '7187', 'p', '961', 'k', 'k', '423', '5999', '4697', '6251', '6441', '1821', 's', 's', 'f', '5365', 'z', '5113', 'y', 'k', 'i', '5627', 'u', 'w', '4103', '8035', '7105', 'o', 'n', 's', 'y']

SOLUTION: c, f, i, k, n, o, p, s, u, w, y, z

PROBLEM: ['5287', 'z', '3495', 'u', '7801', '8849', 'c', 'e', 'n', 'd', '3277', 'k', 'y', '3833', '4727', 'e', '7215', 'v', '1293', '3361', 'z', '7539', 'd', '6455', 'e', 'd', '3633', 'j', '9805', '9597', '6337', 't', '4375', '8053']

SOLUTION:
c, d, e, j, k, n, t, u, v, y, z