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.
word = input()

if len(word) < 3:
    print('NO')
else:
    i1 = word.find('AB')
    i2 = word.rfind('BA')

    if -1 in (i1, i2):
        print('NO')
    else:
        print('YES' if abs(i1 - i2) >= 2 else 'NO')
