Definition: 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.
Input: ['4253', '5763', 'm', '2145', '4783', 'b', '7475', 'x', '9937', '253', 'f', '2861', 'n', 'k', '6273', '5279', '9533', 'u', 'j', 'n', '8711', 'm', 'p', 'z', '9899', '8267', 'i', '2813', '8367', 'v', '7909', 'u', '3503', '843', '4663', 'd', '1039']
Output:
b, d, f, i, j, k, m, n, p, u, v, x, z