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.

['477', '3931', 'g', '5967', 'm', '9845', '1607', 'a', '1749', 'k', 'j', '7945', '9125', 'v', 'n', 's', '5185', '1117', '17', 'x', '4149']
a, g, j, k, m, n, s, v, x

['749', 'r', 'a', 's', 't', '5905', 'm', 'd', '8437', '4583']
a, d, m, r, s, t

['231', 'r', '5673', 'j', '589', 'z', '4659', 'a', '3763']

a, j, r, z