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', 'h', 'z', 'n', 'e', 'y', 't', '4371', 'm', '1059', '4853', '8529', 'l']

SOLUTION: e, h, l, m, n, o, t, y, z

PROBLEM: ['815', '6967', '6553', 'r', 'y', '3641', 'q', 'b', '6131', '4289', 'w', '6093', '6055', 'i', 'b', 'y', '5107', 'v', 'g', '9709', 'x', 'i']

SOLUTION: b, g, i, q, r, v, w, x, y

PROBLEM: ['e', '8391', '7065', '6141', '3335', 't', 'i', 'c', '1791', '6333', 'b', 'z', '1621', 'e', 'h', 'u', 'o', 'q', '3195', '6507', '3253', 'c', '2067', '3917', '7111', 'r', 'j', 'd', '3987', '9139', 'm', '981', 'l', 'f', '2417', 'w', '9983', 'h', 'd', '6021', 'a', 'f']

SOLUTION:
a, b, c, d, e, f, h, i, j, l, m, o, q, r, t, u, w, z