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: ['j', 's', 'z', 'v', '5401', 'u', '8859', 'i', 'l', 'a', 'p', 'v', 'v', 'o', '3969', '4091', 'y', '6827', '1799', '5163', 'd', 'w', '4795', '5167', 'x', 'q', '2903', '1171', '5279', '449', '7901', 'u']

SOLUTION: a, d, i, j, l, o, p, q, s, u, v, w, x, y, z

PROBLEM: ['r', 's', '3409', 'a', 'e', '6855', 'i', 'n', '8655', 's', 't', '8401', 'u', '9603', '8815', 'q', 'a', 'x', 'i', '8455', 'e', '5877', '3917', 'p']

SOLUTION: a, e, i, n, p, q, r, s, t, u, x

PROBLEM: ['6939', '7997', '5', '6347', 'p', '3775', 'y', '7581', 'o', 'x', 'k', '9265', '3697', 'o', 't', 'o', '8635', '8493', '9789', 'r', 'x', 'g', '781', 'd', '8007', 'a', 'f', '3391', 'p', 'k', '6951', 'l']

SOLUTION:
a, d, f, g, k, l, o, p, r, t, x, y