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.

Example Input: DTAWLIdITaWlAkuGndOAZKBCX, ZUIbfylXAdITaWlAkuGndOmCVv
Example Output: a, b, c, d, f, g, i, k, l, m, n, o, t, u, v, w, x, y, z

Example Input: CIqhsYulyDKyZzjvfCmdeetLYRo, zRoQnvhsYulyDKyZzjvfCyCbiwVupwrxnZ
Example Output: b, c, d, f, h, i, j, k, l, n, o, p, q, r, s, u, v, w, x, y, z

Example Input: vihCnmPbbnyFtHyUJUuPttzXqz, ifUPbbnyFtHyUZE
Example Output:
b, c, f, h, i, j, m, n, p, q, t, u, v, x, y, z