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='ABABA'
try:
    if a.index('AB')>-1 and a.index('BA',a.index('AB')+2) >-1:
        print('YES')
except:
    print('NO')