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.
a = input()


def solve():
    q = a.find('AB')
    e = a.find('BA')
    if q == e:
        return 'NO'
    else:
        return 'YES'


if 'AB' in a and 'BA' in a:
    print(solve())
else:
    print('NO')