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 ab(s):
    if 'AB' in s:
        s = s.replace('AB')
        if 'BA' in s:
            return 1
    return 0
def ba(s):
    if 'BA' in s:
        s = s.replace('BA')
        if 'AB' in s:
            return 1
    return 0
        

s = input()
if ab(s) or ba(s):
    print('YES')
else:
    print('NO')
