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.

['1971', 'g', 't', 't', 'x', 'q', 'o', 'm', 'h', '9481', '1729', '5527', 'u', '3157', 's', '8795', 'z', 'g', 'i', '1649', 'p', '65', 's', 'u', '6843', 'r', 'l', 'k', 'n', 's', 'm', '7991', 'u', 'a']
a, g, h, i, k, l, m, n, o, p, q, r, s, t, u, x, z

['1657', 'u', '1849', '425', 'v', '6435', 'j', '2985', '921', '9553', '2621', 'i', '7103', 'd', '8563', 'l', 'b', '6727', '4235', 'n', '8021', 'd', 'z', '437', 'm', '5695', 't', '3421', 'e', 'a', '2941', '791', '1417', '9247', 'h']
a, b, d, e, h, i, j, l, m, n, t, u, v, z

['3931', 'x', '9771', '8081', '3117', '4383', '1103', 's', 'i', '1535', 'c', '221', 'u', 'c', '9307', '737', '1781', '5719', '6089', '4351', '7121', 'k', 'l', '6483', 'e', '5847', '2189', '7069', '75', 'o', 't', 'h', 'z', 'w', '9', '5099', '1293', '1863']

c, e, h, i, k, l, o, s, t, u, w, x, z