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.
One example: ['8129', 'a', '4245', 'y', 'm', 'a']
Solution is here: a, m, y
Explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Now, solve this: ['7257', 'n', '1455', 'g', 'm', 'a', '8279', '1997', '8701', 'u', '877', 'v', 'r', '6593', 'q', '355', 'e', '3905', 'c', 'p', '8801', 'r', '6059', 'd', 'l', '815', 'w', '7971', 'a', '4451', '3175', '5967', 't', '6299', 'k', '4615', 'n', '7255', 't', '5361', '2797', 'v', '4483', '3821']
Solution:
a, c, d, e, g, k, l, m, n, p, q, r, t, u, v, w