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.

Q: ['2521', '8027', 'm', '193', '615', 'l', '1947', '5949', '6307', 'r', '1015', '743', 'v', '6949', 'b', 'g', '8841', 'c', 'b', '2879']

A: b, c, g, l, m, r, v
****
Q: ['o', '1217', '449', 'n', 'e', 'o', 't', '9043', '1925', '5687', '7197', '7943', 'u', '5053', 'q', 'e', '89', 'l', 'h', '3083', '4295', 'o', 'n', '6309', '743', 'n', 'j', '2105', 's', '6845', 'p', 'p', '1355', '3757', 'v', 'f', '961', '4623', '4633', 'p', '4593', 'p', '7337', 'o', 'u']

A: e, f, h, j, l, n, o, p, q, s, t, u, v
****
Q: ['u', 't', '8151', 'y', 'u', 'q', 'l', '8669', '5685', '3517', '2157', 'p', 'z', '305', '147', 'r', '6045', '785', 'd', 'm', 'l', 'v', 'r', 'k', 'j', 'h', 'k', 'g', 'd', '955', '697', '8807', 'o', 'x', 'c', '2925', '2379', '7231', 'b', '4349', 'j', 'x', '5873']

A:
b, c, d, g, h, j, k, l, m, o, p, q, r, t, u, v, x, y, z
****