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.
x = input()
c=0
if 'AB' in x:
    fir = x.find('AB')
    x = x[:fir] + x[fir+2:]
    c+=1
if 'BA' in x:
    sec = x.find('BA')
    c+=1
print('YES' if c==2 else 'NO')