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: ['6655', '7445', '1795', '7495', 'h', 'z', 'u', '2199', 'r', 'p', '2245']

SOLUTION: h, p, r, u, z

PROBLEM: ['9013', 'e', 'm', 'p', 'k', '161', 'k']

SOLUTION: e, k, m, p

PROBLEM: ['7921', '4657', '159', '221', '1777', 'm', '6757', 'x', '8747', '2517', 'n', 'x', 'n', 'q', '49', '9969', '8347', 'c', '3725', '9347', 'g', 'f', '1827', '3015']

SOLUTION:
c, f, g, m, n, q, x