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: ['t', 'h', '6141', 'g', 'f', 'z', 'n', 'b', 'k', '9059', 'y', 'p', '4289', '2683', 'a', '3267', 'w', 'p', 't', '3623', '7759', 'a', 'o', 'm', '9815', 'q', 'u', '8051', '6871']

SOLUTION: a, b, f, g, h, k, m, n, o, p, q, t, u, w, y, z

PROBLEM: ['747', '5385', '5313', 'p', '9581', 'r', '1339', '3919', 'e', 'e', '8057', '7739', 'i', 'e', '3311', '963', 'g', 'h', '7349', 'y', '1493', 'e', '3055']

SOLUTION: e, g, h, i, p, r, y

PROBLEM: ['2783', '3251', 'w', 't', '2313', '2107', 'c', '9953', 'h', 'i', '4789', '189', '3693', 'f', '4225', 'm', '9043', 'g', '6165', 'j', 'v', '8523', '9077', '5699', 'q']

SOLUTION:
c, f, g, h, i, j, m, q, t, v, w