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()
k = False
k1 = False
i = 0


while i < len(a):
    i += 1
    if a[i-1:i+1] == 'BA':
        k = True
        i += 1
    if a[i-1:i+1] == 'AB':
        k1 = True
        i += 1


if k == True and k1 == True:
    print('YES')
else:
    print('NO')
