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.
a = input()
found_AB = False
found_BA = False
pos_AB = -1

for i in range(len(a)-1):
    if a[i:i+2] == 'AB' and not found_BA:
        found_AB = True
        pos_AB = i
    if a[i:i+2] == 'BA' and not found_AB:
        found_BA = True

if found_AB and found_BA and abs(pos_AB - a.find('BA')) > 1:
    print('YES')
else:
    print('NO')
