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.

['8051', 'h', 'g', 's', 't', 'p', 'w', 'x', 's', '8521', 'm', '9719', 'j', 'n', 'i']
g, h, i, j, m, n, p, s, t, w, x

['395', '8309', 'v', 'r', 'x', 'j', 'l', 'b', 'c', 'c', '3123', 't', 'a']
a, b, c, j, l, r, t, v, x

['a', 'y', '1047', 'v', 't', 'd', 'j', 'l', 'l', 'x', 'h', '8139', 'w', 'h', 'o', 'g', 'j', '4203', 'k', '6769', '2997']

a, d, g, h, j, k, l, o, t, v, w, x, y