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: ['887', 'p', '3819', '2727', '1407', 'b', 'n', '737', 'd', 'w', 'q', '6877']

SOLUTION: b, d, n, p, q, w

PROBLEM: ['v', '5433', 'v', '6749', '7491', 'i', 'm', 'e', '5815', '8423', '833', '7359', 'm', 'i', 'f', 'u', 'p', 'j', 't', '3171', '6165', 'q', 'a', '9475', 'm', 'q', '5995', '8443']

SOLUTION: a, e, f, i, j, m, p, q, t, u, v

PROBLEM: ['z', 'o', '9905', '8779', '219', 'm', 'g', 'n', '6401', 'm', 'l', '7657', 'g', '8681', '9149', '6161', 'l', '4347', '4683', '6875', '8911', 'a', 'y', 's', '2367', 'v', '119', 'e']

SOLUTION:
a, e, g, l, m, n, o, s, v, y, z