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()
if "AB" in s : 
    s = s.replace('AB','',1)
    if 'BA' in s : 
        print('YES')
    else : 
        print('NO')
else : 
    print('NO')