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: ['6463', '871', '5781', '283', '9653', 'f', '9661', '3365', '2889', '5499']

SOLUTION: f

PROBLEM: ['3035', 'f', 'k', 'e', '3023', 'p', '9667', '5277', '4757', '8433', 'g', '1399', '7721', 'n', 'p', '7469', '7581', '5679', 'g', 'q']

SOLUTION: e, f, g, k, n, p, q

PROBLEM: ['9909', 'a', 'e', 'v', 'i', '4771', '4065', 't', '3889', 's', '9009', '3969', 'z', 'y', '6859', '8161', '2539', '3053', 'm', 'a', '9401', 'r', 'd', 'w', 'v', 'j', 'f', '2889', 'j', 'a', '6289', 'l', '3591', '5151', 'g', '381', 'q', '125', '8363', 'z', '6769', 'y', '295', 'e', 'f']

SOLUTION:
a, d, e, f, g, i, j, l, m, q, r, s, t, v, w, y, z