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: ['n', '7337', '6887', '2203', '4663', '2837', '6451', '959', '8027', 'p', 'v', 'q', 'g', '8059', '6151', 'v', '7097', '6583', '7637', '2367', 'w', '9603', '5365', '3773', '1707', 'k', 'x', 's', 'c', 'u', '3641', '6137', '1207', 'k', '5531', '4543']

SOLUTION: c, g, k, n, p, q, s, u, v, w, x

PROBLEM: ['w', '1081', 'n', '2073', 't', '6351', '5591', 'a', '113', 'w', 'q']

SOLUTION: a, n, q, t, w

PROBLEM: ['j', 'k', '3095', '319', '2341', 'i', 'w', 'j', 's', '5647', 'l', 'v', '9833', '3901', '2187', 'j', 't', 'h', '9863', '3173', '3191', 'd', 'f', '4049', '9825', '7381', 'u', '1139']

SOLUTION:
d, f, h, i, j, k, l, s, t, u, v, w