Given the task definition and input, reply with output. In this task, you are given two strings A,B. Find the longer of the two lists, convert it to lowercase, and return all the unique alphabets used in it. The two input strings are never equal.

nhdpmehgessFITJMHanKNUBKJtEyZjlBjFld, unzhuuXKahITJMHanKNUBKGeAYrYNThGu

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
a, b, d, e, f, g, h, i, j, k, l, m, n, p, s, t, u, y, z