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.
l = input()
f = False
s = False
i = 0
while i < len(l) - 1:
    if f and l[i] + l[i + 1] == 'BA':
        s = True
        break

    if l[i] + l[i + 1] == 'AB':
        f = True
        i += 1

    i += 1

if not (f and s):
    f = False
    s = False
    i = 0
    while i < len(l) - 1:
        if f and l[i] + l[i + 1] == 'AB':
            s = True
            break

        if l[i] + l[i + 1] == 'BA':
            f = True
            i += 1

        i += 1
if f and s:
    print("YES")
else:
    print("NO")