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[:a.index('AB')]+a[a.index('AB')+1:]
    if 'BA' in a:
        print('YES')
    else:
        print('NO')
else:print('NO')