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: falHsspAHSiE, FTJblHsspsC
Example Output: a, e, f, h, i, l, p, s

Example Input: AKBVukTgKpHndiXHUDkBXsenOHgP, npvrAYqBJjNgKpHndiXHUDBub
Example Output: a, b, d, e, g, h, i, k, n, o, p, s, t, u, v, x

Example Input: mthKDLOfvQTQsuxLNnqybysDtNvilRAdW, vTekfgociYOfvQTQsuxLNnqyboTJtpYrzrL
Example Output:
b, c, e, f, g, i, j, k, l, n, o, p, q, r, s, t, u, v, x, y, z