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.

['2459', '3709', 'f', '8673', '9313', 'm', 'd', 'g', 'c', 'g', 'u', 'f', 'p', 'i', '8771', '3613', '9669', '6221', '1211', '8331', '2295', 'b', 'f', 'm', '1377', '9831', '1751', 'k', '4831', 'm', '2747', '3435', '4543', 'c', '1729', 'e', '7093', '397', 'm', '383', '2019']
b, c, d, e, f, g, i, k, m, p, u

['1799', '6409', '9257', '5923', 'm', 'j', '2565', '715']
j, m

['m', 'f', 'd', 'w', '4769', 'l', '3991', 'n', '8157', 's', 'e', '6721', 'b', '8003', 'y', 'r', 'v', '1415', '6251', '9951', 'g', 'u', 'f']

b, d, e, f, g, l, m, n, r, s, u, v, w, y