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()
for i in range(0, len(a) - 1):
    if a[i] == 'A' and a[i + 1] == 'B':
        a = a.replace(a[i], 'x', 1)
        a = a.replace(a[i + 1], 'y', 1)
if 'BA' in a:
    print('YES')
else:
    print('NO')
