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' not in s or 'BA' not in s:
    print('NO')
else:
    n=len(s)
    i=s.index('AB')
    j=n-s[::-1].index('AB')-1
    # ABA => i=0 j=2
    # BAB => i=1 j=1
    #ABBA => i=0 j=3
    #BAAB => i=2 j=1
    if j<i or j-i>2:
        print('YES')
    else:
        print('NO')