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 = input()

def contains_non_overlapping(s):
    ab_index = s.find('AB')
    if ab_index != -1 and s.find('BA', ab_index + 2) != -1:
        return 'YES'
    
    ba_index = s.find('BA')
    if ba_index != -1 and s.find('AB', ba_index + 2) != -1:
        return 'YES'
    
    return 'NO'

print(contains_non_overlapping(s))
