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: ['7777', '6223', 'k', 'k', 'd', '9743', '189', '7705', 'c', '6115', '4275']

A: c, d, k
****
Q: ['w', 'n', '729', '2491', 'n', 'x', '915', '1869', 'z', '8491', '9947', '561', '829', 'n', 't', 'i']

A: i, n, t, w, x, z
****
Q: ['6861', 'j', 'g', 'c', 'i', '1333', 'j', '8155', '9669', 'a', 'd', 'g', '7769', 's', 'm', '9635', 'f', 'e', 'j', 'r', '7973', 'k', 'o', '8709', '4937', 'j', '8441', '4163', 'k', 'u']

A:
a, c, d, e, f, g, i, j, k, m, o, r, s, u
****