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: ['g', 'u', 'q', '1375', '9491', 't', 'w', 'c', 'v', 'y', '3169', '1607']

SOLUTION: c, g, q, t, u, v, w, y

PROBLEM: ['o', '5503', '5837', '4539', '7631', 'm', '2641', 'p', '7901', '8117', 'z', '3373', '3215', 'v', 'a', '5949', 'w', '9049', 'd', 'a', 'l', 'v', 'l', 'n', 'w', 'r', 'j', '9031', '9609', '4209', 'c', '7453', '5855', '2883', '5941', 't', '4283', 'x', 'x', 'n', 'c']

SOLUTION: a, c, d, j, l, m, n, o, p, r, t, v, w, x, z

PROBLEM: ['9941', 'p', 'v', 'c']

SOLUTION:
c, p, v

