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: ['5039', '2227', 't', 'o', '3313', 'm', 'v', '637', '6773', 'v', 'c', 'l', 'y', 'u', '3823', '9669', 'k', 'h', '3589', 'b', 'i', '3833', 's', 'm', '8201', 'u', '3143', 'k', '4111', '9769', '425', '4339', '209', 'c', 'c', '669', '8201', 'u', '7443', '2387', '6919', 'b', 'b', '2873']

SOLUTION: b, c, h, i, k, l, m, o, s, t, u, v, y

PROBLEM: ['9', '6367', '1833', 'x', 'l', 'u', '4603', 'h', '7833', 'v', 'f', '2399', 'l', '433', 'p', '7021', 'q', 'u', '387', 'k', 'd', 'f', 't', 't', 'm', '6553', 'w', 'p']

SOLUTION:
d, f, h, k, l, m, p, q, t, u, v, w, x