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: ['2293', 'p', '9787', '7241', '8689', 'u', '3141', 'h', 'c', 'b', 'f', 's', '319', 'c', 'p', '6909', 'p', 'f', '1717', 'd', '2285', 's']

SOLUTION: b, c, d, f, h, p, s, u

PROBLEM: ['f', '7573', '2067', 'n', '3671', '7969', '7889', '4893', '6501', 'l', 'y', '4331', 'a', 'e', '2081', '3863', 't', 'j', '7921', 's', '7203', '7797', 'f', '4279', '1299', '987', '5003', '9071', '9559', '6061', '1889', '2653', 'm', 'w', '665', '7343', '9763', 'r', '6343', '9393', '9289']

SOLUTION: a, e, f, j, l, m, n, r, s, t, w, y

PROBLEM: ['y', 'y', 'b', 't', '477', '4417', 'q', '6347', 'r', 'g', 'h', 'v', '5397', '2701', '8839', '8849', '4243', '3885', '4475', '2507', '9609', 'e', '1071', 'c', 't', '3143', '407', 'x']

SOLUTION:
b, c, e, g, h, q, r, t, v, x, y