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()
n=len(s)
try:
    i=s.index('AB')
    j=n-1-s[::-1].index('AB')
    i1=s.index('BA')
    j2=n-1-s[::-1].index('BA')
    if j<i or j>=i+3 or j1<i1 or j1>=i1+3:
        print('YES')
    else:
        print('NO')
except:
    print('NO')