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()


flag = False
ab=False
ba=False
i = 0
try:
    x1 = word.index('AB')
    x2 = word[x1+2:].index('BA')
    print('YES')
except ValueError:
    try:
        y1 = word.index('AB')
        y2 = word[y1+2:].index('BA')
        print('YES')
    except ValueError:
        print('NO')