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

for i in range(len(a)-1):
    if a[i:i+2] == 'AB':
        found_AB = True
        if i+2 < len(a) and a[i+2:].find('BA') != -1:
            found_BA = True
            break

    if a[i:i+2] == 'BA':
        found_BA = True
        if i+2 < len(a) and a[i+2:].find('AB') != -1:
            found_AB = True
            break

if found_AB and found_BA:
    print('YES')
else:
    print('NO')
