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()
if 'AB' in a:
    a = a.replace('AB', '!', 1)
if 'BA' in a:
    a = a.replace('BA', '?', 1)
if '!' in a and '?' in a:
    print('YES')
else:
    print('NO')
