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: ['x', '4283', 'n', 'b', 'g', 'p', '8305', '7781', '5907', 's', '1305', 'w', '8623', 'o', 'c', 'u', '1839', '2869', '7537', 'y', '2395', '5309', 'e', '4059', 'l', '6647', 'p', '9717', 'y', 'y', '3769', '2527', '2981', '5255', '4063', 'j', '4843', 'j', '9355', 'z']

SOLUTION: b, c, e, g, j, l, n, o, p, s, u, w, x, y, z

PROBLEM: ['2103', '7937', 'v', '7641', '6609', '269', '4463', '4333', 'c', '8407', '4883', '6283', 'a', '8643', '3365', '1929', 'v', 'o', '2107', '7453', '9157', '5581', '5187', 'f', 'k', '8227', '6295', 'b', 'y', '4995', '1187', 'k', 'n', 'p', 'z', '8165', 'n', '7345', 'l']

SOLUTION: a, b, c, f, k, l, n, o, p, v, y, z

PROBLEM: ['8385', '8077', 'q', 't', '9815', 'v', '3753', '4867', '6037', '6041', 'a', 'n', '8161', 'k']

SOLUTION:
a, k, n, q, t, v