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: ['1627', 'r', '2429', 'b', '4451', 's', 'k', 'm', '269', 'l', '709', 's', 'q', '985', 'x', 'j', 'k', 'k', '6603', 'v', '9497', '477', '5803', 'c', 't', 'f', '3189', '6419', '8561', '5709', 'u', 'z', '5717', '9711', 'w', 'y', 'm', 'v']

SOLUTION: b, c, f, j, k, l, m, q, r, s, t, u, v, w, x, y, z

PROBLEM: ['b', 't', '2199', 'e', 'i', '1883', '5137', '8495', 't', '7377', 'm', '7665', '2009', 'o', '3757', 'm', '861', 'm', 'l', '9229', 'c', 'r', 'q', 'i', 'm', '705', 'b', '4301', 'd', 'l', 'f', '5485', 'h', 'p', '4529', '7879', 'f', 'b', 'm']

SOLUTION: b, c, d, e, f, h, i, l, m, o, p, q, r, t

PROBLEM: ['z', 'r', 't', '2101', 'l', 'y', 'v', 'x', '1973', 'g', '5307', 'x', '4467', 's', '8179', 'j', '6507']

SOLUTION:
g, j, l, r, s, t, v, x, y, z