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().casefold()
if 'ab' in s:
    if 'ba' in s and len(s)>4:
        print('YES')
    else:
        print('NO')
elif 'ba' in s:
    if 'ab' in s and len(s)>4:
        print('YES')
    else:
        print('NO')
else:
    print('NO')
    