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.
Example: ['8129', 'a', '4245', 'y', 'm', 'a']
Example solution: a, m, y
Example explanation: Here, the unique alphabets in the list are 'a', 'y', and 'm', hence their sorted order is 'a, m, y'.

Problem: ['m', '4239', '311', 'a', 'u', '3053', 'n', '4143', 'n', 'r', '9101', '4619', 'l', '1455', '7233', 'a', '2225', 'e', '7613', 'f', '1375', 'm', 's', '1967', '3801', '301', 't', '7691', '3531', '6773', 's', 'y', '5681', '3435', '7949', '5165', '8557', '8363', '5361', '1593', '3291', '2087', '295', '3975']
Solution: a, e, f, l, m, n, r, s, t, u, y