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.

['i', '9215', 'n', 'p', '4815', '8757', 'm', '1755', 'c', 'z']
c, i, m, n, p, z

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

['c', '4555', 'a', 'y', 'r', 'v', 'q', 'q', '429', 'w', '3869', '7761', '6551', '9067', '1137', '9133', '27', 'm', 'g', 'z', 'b', '1355', '5425', '5475', 'v', 'f', 'i', '4087', 'c', 'p']

a, b, c, f, g, i, m, p, q, r, v, w, y, z