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: ['z', '2519', '4799', '4715', '7165', 'r', 'r', 'l', 'n', '6925', '8935', '9795', '5489', 'v', 'u', '6527', '2241', 'u', 'c', 'w', '9755', 'w', '9823', 'g']

SOLUTION: c, g, l, n, r, u, v, w, z

PROBLEM: ['k', '8917', '3773', '6723', 'r', 'z', '3265', 'o', 'f', 'q', '9343', 'f', '1925', 'u', 'b', 'o', '5275', 'b', 'n', 'd', 'j', '4825']

SOLUTION: b, d, f, j, k, n, o, q, r, u, z

PROBLEM: ['f', '3177', 'q', '2339', 'w', '9045', '847', '2551', 'z', '415', '7153', '9909', 'v', '3613', 'z', 's', 'z', '7057', 'k', '8205', 'h', 'j', '333', '7427', 'z', 'g', 'z', 'v', '5679', 'v', 'w', '4651', '8981']

SOLUTION:
f, g, h, j, k, q, s, v, w, z