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', 'p', '2925', 'n', 'o', 'y', '6381', 'l', '4963', 'g', 'm', 'u', 't', '9389', '3787', '7713', '1251', '779', 'i', 'w', '9869', 'y', 'y', '3881', 'k', 't']

SOLUTION: g, i, k, l, m, n, o, p, t, u, w, y

PROBLEM: ['9403', '9881', '8391', 't', '1793', 'w', 'x', 'y', '6383', 'j', 'r', '5323', 'r', 'l', 'e', 'u', '7193', '2309', '837', 'z', 'w', 'n', '4427', '8269', '6333', 'a', 'p', '1933', '8497', '2665', '1349', '6807', '9009', 'b']

SOLUTION: a, b, e, j, l, n, p, r, t, u, w, x, y, z

PROBLEM: ['z', 'l', '1743', 'm', 'l', 'k', 'd', 'm', 's', 'k', 'w', '5979', '657', 'n', '1919', 'x', 'h', '393', '9527', 'u', '3387', 'k', '9215', '1909', '7385', '4371', '9459', '5377', 'w', 'z', '3803', 'h', '9091', 'c']

SOLUTION:
c, d, h, k, l, m, n, s, u, w, x, z