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()
Flag = True
if s.count('AB') == 0 or s.count('BA') == 0:
    Flag = False
elif s.replace('AB', '', 1).count('BA') == 0 and s.replace('BA', '', 1).count('AB') == 0:
    Flag = False
print('YES' if Flag else 'NO')