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()
ab = []
ba = []
for i in range(0, len(s)):
    if s[i:i+2] == 'AB':
        ab.append(i)
    if s[i:i+2] == 'BA':
        ba.append(i)

if (len(ab) != 0 and len(ba) != 0) and ((min(ab) + 1 != max(ba)) or (max(ab) + 1 != min(ba))):
    print('YES')
else:
    print('NO') 