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 = str(input())

def foobar(string):
    ab = string.find('AB')
    ba = string.find('BA')
    if ab == -1 or ba == -1:
        return 'NO'
    if abs(ab - ba) < 2:
        ba2 = string.find('BA', ab+2)
        if ba2 != -1:
            return 'YES' 
        ab2 = string.find('AB', ba+2)
        if ab2 != -1:
            return 'YES'     

    if ba + 1 < ab or ab + 1 < ba:
        return 'YES'
    return 'NO'

print(foobar(s))