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.


def __main__():
    s = input()
    AB = []
    BA = []

    for i in range(len(s) - 1):
        if(s[i] == 'A' and s[i + 1] == 'B'):
            AB.append(i)
        if (s[i] == 'B' and s[i + 1] == 'A'):
            BA.append(i)


    if(len(AB) == 0 or len(BA) == 0):
        print('NO')
        return

    if(AB[-1] - BA[0] > 1 or BA[-1] - AB[0] > 1):
        print('YES')
        return

    print('NO')
    return

__main__()