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: ['w', 'o', 'l', '5331', 'k', '9325', '6759', '7931', '8185', 'w', 'h', 'h', 'x', '4357', '6845', 'v', 'o', '8401', 'u', 'g', 'f', 'j', 'j', '2493', '4753', 'c', 'm', '1469', '4307', 'm', '2737', 'n', 'y']

SOLUTION: c, f, g, h, j, k, l, m, n, o, u, v, w, x, y

PROBLEM: ['e', 'c', '4241', '2685', 'o', '9859', 'z', '2647', 'b', 'c', 'y', '1985', '5985', '5709', '6655', 'q', 'z', '9933', '6817', '6477', '1837', 'x', 'p', '9251', '3787', 'v', '5741', 'e', 'p', '493', '5949', '5519', 'v', 'g', '1403', 'z', 'h', 'z']

SOLUTION: b, c, e, g, h, o, p, q, v, x, y, z

PROBLEM: ['o', '8511', '6657', '4545', '6417', 'u', '1683', '9329', 's', 'a', '4139', 'w', 's', 'i', '3943', '3881', '3971', '9041', 'f', 'a', 'm', '3199', 'e', '783', 'v', 'y', 'h', '5825', 'e', '7913', '3855', 'r', '1', 'v', '1801', '8789', '9885', '5131', 'k', '725']

SOLUTION:
a, e, f, h, i, k, m, o, r, s, u, v, w, y