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.

['815', '6967', '6553', 'r', 'y', '3641', 'q', 'b', '6131', '4289', 'w', '6093', '6055', 'i', 'b', 'y', '5107', 'v', 'g', '9709', 'x', 'i']
b, g, i, q, r, v, w, x, y

['5553', 'f', '3881', '8867', 's', 'd', 'a', '375', '7889', '3949', '2905', 'w', 'q', 'q', 'd', '4203', 'i', '2601', 'y', 'p', 'k']
a, d, f, i, k, p, q, s, w, y

['s', 'v', '2349', 't', '6663', '7207', 'r', '3045', 'l', '835', '8641', 'i', 'j', '9575', '8321', 'n', '4559', '3603', '8883', 'z', '5381', 't', '3031', 'd', 'g', '9599', '2975']

d, g, i, j, l, n, r, s, t, v, z