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: ['9351', 'v', 'h', 'z', 'g', 'f', 't', 'q', 'g', 'o', '4073', 'n', '6149', '1735', '157', 'm']

SOLUTION: f, g, h, m, n, o, q, t, v, z

PROBLEM: ['y', '8115', 'f', '5333', 'f', '3437', 'b', 'e', '5719', 'm', 'w', '95', '4863', 'k', '4895', 'a', '8179', 'm', '7919', '1731', '229', 'r', '1847', '7559', '6669']

SOLUTION: a, b, e, f, k, m, r, w, y

PROBLEM: ['s', '8793', 't', '8957', 'c', '8595', 'm', '7967', '6015', 'n', 'j', '983', 'f', '8383', 'z', '4941', '2079', '4945', '8375', 'o', 's', 'i', '4337', 'c', '3793', 'n', '1647', '567', 'h', '5603', 'n', 'l', '181', '4257', 'b']

SOLUTION:
b, c, f, h, i, j, l, m, n, o, s, t, z