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 = list(input())


def f(s):
    e = False
    for i in range(len(s) - 1):
        if s[i] == 'A' and s[i + 1] == 'B':
            e = True
        if s[i + 1] == 'A' and s[i] == 'B':
            e = True
        if i != 0:
            if s[i] == s[len(s) - i]:
                e = False
    if e:
        return 'YES'
    return 'NO'


print(f(s))