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()
flag1 = False
if s.find('AB') != -1:
    flag1 = True
flag2 = False
if s.find('BA') != -1:
    flag2 = True
s = s.replace('ABA', '1')
if s.find('1') == -1 and flag1 and flag2:
    print('YES')
else:
    print('NO')