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: ['v', '6635', '5395', '3263', '4391', 'h', '1521', 'f', '9861', '6125', '1673', '3679', '8681', '4967', 'f', 'a', 'c', 'k', 'n', '4155', 'e', 'm', 'i', '1699', 'r', 'f', 'u', 'r', '3451', 'v', '7239', 'o', '4359', 'l', 'a', '2925']

SOLUTION: a, c, e, f, h, i, k, l, m, n, o, r, u, v

PROBLEM: ['907', '2407', '1385', '3593', 'x', '4143', '2271', '8361', 'q', '5093', 'd', '257', 'm', 'a', '5751', '7845', '3925', '3517', '7753', 'e', '5803', '2629', 't', 'e', '845', '6157', '9787', '225', 'j', 'j', 'l', '1321', 'k', '2459', 'u', '9113', '3193', 'a', 'j', 't']

SOLUTION: a, d, e, j, k, l, m, q, t, u, x

PROBLEM: ['6339', '4793', 'w', '1569', '8113', 'u', '7967', '4565', '7763', '3787', '5393', '1153', 'x', '5679', 'x', 't', 'z', '7547']

SOLUTION:
t, u, w, x, z