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: ['4299', 'b', '4171', '7639', '6609', '927', '5249', 'o', 'p', '9851', 'e', '1311', '3777', '7799', '7687', '8809', 'c', 'r', '47', '1925', '1847', 'r', 'd', 'r', '1871', '5935', 'r', '2283', 'p', 'p', '2727', 'c', 'i', '7357', 'y', '5103', '6115', 'q', 'w', 'u', '9201', '4221', '7717', 'o']

SOLUTION: b, c, d, e, i, o, p, q, r, u, w, y

PROBLEM: ['2313', '2073', 'd', 'e', 'o', '793', '4999', 'f', 'c', '4473', '4519', 'u', 'n', 'k', '69', '475', 'a', 'j', 'q', 'x', '5869', '9523', 'z', 'v', '9265', '5989', 'p', 'm', 'g', 'y', 'b']

SOLUTION: a, b, c, d, e, f, g, j, k, m, n, o, p, q, u, v, x, y, z

PROBLEM: ['e', '7307', '2797', 'q', '5421', '8189', 'l', 'o', '5583', 't', 'w', '9585', 'y', 'o', '4035', 'm', '2907', '9629', '4571', '817', '4899', '931', '6575', '3679', 's', '2437', 'y', 'p', 'w', '983', '3449', '3637', 'c', '3975', 'q', '9645', '8415', 'p', 't', 'o', '7527', '8355']

SOLUTION:
c, e, l, m, o, p, q, s, t, w, y