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.
s=input()
if 'AB' not in s:
    print('NO')
else:
    ind=s.index('AB')
    s=s[:ind]+s[ind+2:]
    if 'BA' not in s:
        print('NO')
    else:
        print('YES')