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: ['b', 'a', '7411', '4471', 'z', 'l', '2051', 'q', '6749', '8647', 's', 'y', 'h', '9319', 'e', '5419', 'y', 'q']

SOLUTION: a, b, e, h, l, q, s, y, z

PROBLEM: ['v', '2989', 'z', '7843', 'e', '9923', 'y', 'b', '7611', 'u', 'u', '6227', '3145', 'w', '6451', 'g', '3129', 'o', 'r', 'z', '8349', 'u', 'h', 'd', 'g', 'a']

SOLUTION: a, b, d, e, g, h, o, r, u, v, w, y, z

PROBLEM: ['6491', '9847', '2161', '5725', 'g', 't', '8017', 'f', '587', '145', '8061', '7455', 'z', '5013', 'h', '2851', '6513', '827', '4121', 'y', 'n', '1533', '3593', 'j', '8293', 'y', '4381', '6943', '867']

SOLUTION:
f, g, h, j, n, t, y, z

