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: ['o', 'z', 'h', '3965', 'n', '3009', '173', '997', '3987', '5799', '2331', 'p', 'x', '897', '8213', '451', 'u', 't', 't', '9917', '4501', 't', 'c', 'i', 'w', 'w', 'u', '2977', 't', 'b', '4161', '9281', 'w', 'f', '3137', '5745', 'e', '673', '6363', 'h', 'q', 'x', 'm', '9505']

SOLUTION: b, c, e, f, h, i, m, n, o, p, q, t, u, w, x, z

PROBLEM: ['c', '4881', '6893', '3729', 'j', '2385', 'q', 'v']

SOLUTION: c, j, q, v

PROBLEM: ['v', 'q', 'x', '8585', 'o', '8335', 'z', 't', 'z', 'f', 's', 'i', 'r', 'b', '8787', '4993', '6157', 'n', '9551', '6507', '45', 'r', 'j', 'z', '8305', 'v', 't', 'h', 'o', '531', '7489']

SOLUTION:
b, f, h, i, j, n, o, q, r, s, t, v, x, z