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: ['7065', 'q', 't', '3177', '9035', 'i', 'l', 'd', '8961', '1183', '6507', 'u', 'c', 't', '2467', '7659', 'e', '8963', 'j', 'g', 'p', '6779', '7115']

SOLUTION: c, d, e, g, i, j, l, p, q, t, u

PROBLEM: ['h', 'u', 'y', '7677', '9441', '1769', 'v', '1433', 'l', '7739', 'a', '8305', 'n', 'a', '6711', '3161', 'e', 'u', '993', '2211', '4011', 'q', 'o']

SOLUTION: a, e, h, l, n, o, q, u, v, y

PROBLEM: ['2257', '9607', 'o', 'g', 'a', '5413', 'b', '4217', 's', 'l', '7103', '7923', 'u', 'f', '8683', 'a', 't', 'u', 't', '3317', 'l', 'l', '9891', 'g', 'q']

SOLUTION:
a, b, f, g, l, o, q, s, t, u