You are given string *s*. Your task is to determine if the given string *s* contains two non-overlapping substrings "AB" and "BA" (the substrings can go in any order).
The only line of input contains a string *s* of length between 1 and 10<sup class="upper-index">5</sup> consisting of uppercase Latin letters.
def check(s):
    
    ab_index = s.find("AB")
    if ab_index == -1: return "NO"

    ba_index = s.find("BA", ab_index + 2)
    if ba_index == -1: return "NO"

    if ba_index > ab_index + 1: return "YES"

    ba_index = s.find("BA")
    if ba_index == -1: return "NO"

    ab_index = s.find("AB", ba_index + 2)
    if ab_index == -1: return "NO"

    if ab_index > ba_index + 1: return "YES"

    return "NO"

s = input().strip()
print(check(s))
