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: ['f', 't', '2135', '8397', '6361', '389', '2253', 'x', 'p', '4833', '5785', 'x', '1811', '9639', '5739', '175', '3231', '5931', 'r', 'c', 'g', 'h', 'p', '909', 'p', '587', 'a', 'a', 'h', 'q', 's', '5945', '4911', 't', 'h', '7517', 'p', '3177', 'h', 'u', '3577', '7055', 'l']

SOLUTION: a, c, f, g, h, l, p, q, r, s, t, u, x

PROBLEM: ['d', '771', '4193', 'e', '1537', 'a', 'q']

SOLUTION: a, d, e, q

PROBLEM: ['8207', 't', 't', '321', '9581', 'j', 'c', '6663', 'z', '3977', 'g', 't', 'p', 'z', '8175', 'w', 'm', 'j', '2023', '3637', 'a', 'g', 'y', '6473', 'q', '8979']

SOLUTION:
a, c, g, j, m, p, q, t, w, y, z