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.
a = input()


def solve():
    n = len(a)
    for i in range(n - 2):
        if (a[i] == 'A' and a[i + 1] == 'B') and a[i + 2] != 'A':
            return 'YES'
        elif (a[i] == 'B' and a[i + 1] == 'A') and a[i + 2] != 'B':
            return 'YES'
    return 'NO'


if 'AB' not in a and 'BA' not in a:
    print('NO')
else:
    print(solve())
