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()

# Search for the first occurrence of "AB" and look for "BA" after that index
if 'AB' in s:
    index_AB = s.index('AB')
    if 'BA' in s[index_AB + 2:]:
        print('YES')
        exit()

# Search for the first occurrence of "BA" and look for "AB" after that index
if 'BA' in s:
    index_BA = s.index('BA')
    if 'AB' in s[index_BA + 2:]:
        print('YES')
        exit()

print('NO')
