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.
q = list(input().split('AB'))
p = 1
for i in range(len(q)):
    if not p:
        break
    if i == 0:
        if 'BA' in q[i][:-2]:
            p = 0
            break
    elif i == len(q) - 1:
        if 'BA' in q[i][1:-1]:
            p = 0
            break
    elif 'BA' in q[i][1:-2]:
        p = 0
        break
if p:
    print('NO')
else:
    print('YES')
